diff --git a/src/app.rs b/src/app.rs
index a41353c..5c6efd4 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -16,7 +16,7 @@ use crate::analytics;
 use crate::computed::{ComputedChannel, ComputedChannelLibrary, FormulaEditorState};
 use crate::parsers::{Aim, EcuMaster, EcuType, Haltech, Link, Parseable, RomRaider, Speeduino};
 use crate::state::{
-    ActiveTool, CacheKey, LoadResult, LoadedFile, LoadingState, ScatterPlotConfig,
+    ActiveTool, CacheKey, FontScale, LoadResult, LoadedFile, LoadingState, ScatterPlotConfig,
     ScatterPlotState, SelectedChannel, Tab, ToastType, CHART_COLORS, COLORBLIND_COLORS,
     MAX_CHANNELS,
 };
@@ -74,6 +74,8 @@ pub struct UltraLogApp {
     // === Unit Preferences ===
     /// User preferences for display units
     pub(crate) unit_preferences: UnitPreferences,
+    /// User preference for UI font size scaling
+    pub(crate) font_scale: FontScale,
     // === Custom Field Normalization ===
     /// Custom user-defined field name mappings (source name -> normalized name)
     pub(crate) custom_normalizations: HashMap<String, String>,
@@ -151,6 +153,7 @@ impl Default for UltraLogApp {
             field_normalization: true, // Enabled by default for better readability
             initial_view_seconds: 60.0, // Start with 60 second view
             unit_preferences: UnitPreferences::default(),
+            font_scale: FontScale::default(),
             custom_normalizations: HashMap::new(),
             show_normalization_editor: false,
             norm_editor_extend_source: String::new(),
@@ -230,6 +233,12 @@ impl UltraLogApp {
         palette[color_index % palette.len()]
     }
 
+    /// Get a scaled font size based on user's font scale preference
+    #[inline]
+    pub fn scaled_font(&self, base_size: f32) -> f32 {
+        (base_size * self.font_scale.multiplier()).round()
+    }
+
     // ========================================================================
     // File Loading
     // ========================================================================
diff --git a/src/state.rs b/src/state.rs
index 9ecdd46..f9fdb23 100644
--- a/src/state.rs
+++ b/src/state.rs
@@ -195,6 +195,32 @@ impl ActiveTool {
     }
 }
 
+/// Font scale preference for UI elements
+#[derive(Clone, Copy, PartialEq, Eq, Default, Debug)]
+pub enum FontScale {
+    /// Smaller fonts (0.85x)
+    Small,
+    /// Default size (1.0x)
+    #[default]
+    Medium,
+    /// Larger fonts (1.2x)
+    Large,
+    /// Extra large fonts (1.4x)
+    ExtraLarge,
+}
+
+impl FontScale {
+    /// Get the multiplier for this font scale
+    pub fn multiplier(&self) -> f32 {
+        match self {
+            FontScale::Small => 0.85,
+            FontScale::Medium => 1.0,
+            FontScale::Large => 1.2,
+            FontScale::ExtraLarge => 1.4,
+        }
+    }
+}
+
 /// A selected point on a heatmap
 #[derive(Clone, Default)]
 pub struct SelectedHeatmapPoint {
diff --git a/src/ui/channels.rs b/src/ui/channels.rs
index f76d196..2fde154 100644
--- a/src/ui/channels.rs
+++ b/src/ui/channels.rs
@@ -9,7 +9,12 @@ use crate::state::MAX_CHANNELS;
 impl UltraLogApp {
     /// Render channel selection panel - fills available space
     pub fn render_channel_selection(&mut self, ui: &mut egui::Ui) {
-        ui.heading("Channels");
+        // Pre-compute scaled font sizes
+        let font_14 = self.scaled_font(14.0);
+        let font_16 = self.scaled_font(16.0);
+        let font_18 = self.scaled_font(18.0);
+
+        ui.label(egui::RichText::new("Channels").heading().size(font_18));
         ui.separator();
 
         // Get active tab info
@@ -31,7 +36,7 @@ impl UltraLogApp {
 
             // Computed Channels button
             if ui
-                .button("+ Computed Channels")
+                .button(egui::RichText::new("+ Computed Channels").size(font_14))
                 .on_hover_text("Create virtual channels from mathematical formulas")
                 .clicked()
             {
@@ -44,7 +49,7 @@ impl UltraLogApp {
             let mut search_text = current_search;
             let mut search_changed = false;
             ui.horizontal(|ui| {
-                ui.label("Search:");
+                ui.label(egui::RichText::new("Search:").size(font_14));
                 let response = ui
                     .add(egui::TextEdit::singleline(&mut search_text).desired_width(f32::INFINITY));
                 search_changed = response.changed();
@@ -58,10 +63,13 @@ impl UltraLogApp {
             ui.add_space(5.0);
 
             // Channel count
-            ui.label(format!(
-                "Selected: {} / {} | Total: {}",
-                selected_count, MAX_CHANNELS, channel_count
-            ));
+            ui.label(
+                egui::RichText::new(format!(
+                    "Selected: {} / {} | Total: {}",
+                    selected_count, MAX_CHANNELS, channel_count
+                ))
+                .size(font_14),
+            );
 
             ui.separator();
 
@@ -173,7 +181,8 @@ impl UltraLogApp {
                                 "📊 Channels with Data ({})",
                                 channels_with.len()
                             ))
-                            .strong(),
+                            .strong()
+                            .size(font_16),
                         )
                         .default_open(true)
                         .show(ui, |ui| {
@@ -203,7 +212,8 @@ impl UltraLogApp {
                                 "📭 Empty Channels ({})",
                                 channels_without.len()
                             ))
-                            .color(egui::Color32::GRAY),
+                            .color(egui::Color32::GRAY)
+                            .size(font_16),
                         )
                         .default_open(false) // Collapsed by default
                         .show(ui, |ui| {
@@ -234,7 +244,8 @@ impl UltraLogApp {
                 ui.label(
                     egui::RichText::new("Select a file to view channels")
                         .italics()
-                        .color(egui::Color32::GRAY),
+                        .color(egui::Color32::GRAY)
+                        .size(font_16),
                 );
             });
         }
@@ -242,7 +253,17 @@ impl UltraLogApp {
 
     /// Render selected channel cards
     pub fn render_selected_channels(&mut self, ui: &mut egui::Ui) {
-        ui.heading("Selected Channels");
+        // Pre-compute scaled font sizes
+        let font_12 = self.scaled_font(12.0);
+        let font_14 = self.scaled_font(14.0);
+        let font_16 = self.scaled_font(16.0);
+        let font_18 = self.scaled_font(18.0);
+
+        ui.label(
+            egui::RichText::new("Selected Channels")
+                .heading()
+                .size(font_18),
+        );
         ui.separator();
 
         let use_normalization = self.field_normalization;
@@ -391,7 +412,8 @@ impl UltraLogApp {
                                     ui.label(
                                         egui::RichText::new(&card.display_name)
                                             .strong()
-                                            .color(card.color),
+                                            .color(card.color)
+                                            .size(font_14),
                                     );
                                     let close_btn = ui.small_button("x");
                                     if close_btn.clicked() {
@@ -408,11 +430,12 @@ impl UltraLogApp {
                                         ui.label(
                                             egui::RichText::new("Min:")
                                                 .color(egui::Color32::GRAY)
-                                                .small(),
+                                                .size(font_12),
                                         );
                                         ui.label(
                                             egui::RichText::new(min_str)
-                                                .color(egui::Color32::LIGHT_GRAY),
+                                                .color(egui::Color32::LIGHT_GRAY)
+                                                .size(font_14),
                                         );
                                         if let (Some(record), Some(time)) =
                                             (card.min_record, card.min_time)
@@ -438,11 +461,12 @@ impl UltraLogApp {
                                         ui.label(
                                             egui::RichText::new("Max:")
                                                 .color(egui::Color32::GRAY)
-                                                .small(),
+                                                .size(font_12),
                                         );
                                         ui.label(
                                             egui::RichText::new(max_str)
-                                                .color(egui::Color32::LIGHT_GRAY),
+                                                .color(egui::Color32::LIGHT_GRAY)
+                                                .size(font_14),
                                         );
                                         if let (Some(record), Some(time)) =
                                             (card.max_record, card.max_time)
@@ -488,7 +512,8 @@ impl UltraLogApp {
             ui.label(
                 egui::RichText::new("Click channels to add them to the chart")
                     .italics()
-                    .color(egui::Color32::GRAY),
+                    .color(egui::Color32::GRAY)
+                    .size(font_16),
             );
         }
     }
diff --git a/src/ui/chart.rs b/src/ui/chart.rs
index 10c3527..7d98d20 100644
--- a/src/ui/chart.rs
+++ b/src/ui/chart.rs
@@ -17,7 +17,7 @@ impl UltraLogApp {
             ui.centered_and_justified(|ui| {
                 ui.label(
                     egui::RichText::new("Select channels to display chart")
-                        .size(20.0)
+                        .size(self.scaled_font(20.0))
                         .color(egui::Color32::GRAY),
                 );
             });
diff --git a/src/ui/histogram.rs b/src/ui/histogram.rs
index b7a7a6b..a03a61b 100644
--- a/src/ui/histogram.rs
+++ b/src/ui/histogram.rs
@@ -90,7 +90,7 @@ impl UltraLogApp {
             ui.centered_and_justified(|ui| {
                 ui.label(
                     egui::RichText::new("Load a log file to use histogram")
-                        .size(20.0)
+                        .size(self.scaled_font(20.0))
                         .color(egui::Color32::GRAY),
                 );
             });
@@ -151,9 +151,13 @@ impl UltraLogApp {
         let mut new_mode: Option<HistogramMode> = None;
         let mut new_grid_size: Option<HistogramGridSize> = None;
 
+        // Pre-compute scaled font sizes
+        let font_14 = self.scaled_font(14.0);
+        let font_15 = self.scaled_font(15.0);
+
         ui.horizontal(|ui| {
             // X Axis selector
-            ui.label(egui::RichText::new("X Axis:").size(15.0));
+            ui.label(egui::RichText::new("X Axis:").size(font_15));
             egui::ComboBox::from_id_salt("histogram_x")
                 .selected_text(
                     egui::RichText::new(
@@ -161,7 +165,7 @@ impl UltraLogApp {
                             .and_then(|i| channel_names.get(&i).map(|n| n.as_str()))
                             .unwrap_or("Select..."),
                     )
-                    .size(14.0),
+                    .size(font_14),
                 )
                 .width(160.0)
                 .show_ui(ui, |ui| {
@@ -169,7 +173,7 @@ impl UltraLogApp {
                         if ui
                             .selectable_label(
                                 current_x == Some(*idx),
-                                egui::RichText::new(name).size(14.0),
+                                egui::RichText::new(name).size(font_14),
                             )
                             .clicked()
                         {
@@ -181,7 +185,7 @@ impl UltraLogApp {
             ui.add_space(16.0);
 
             // Y Axis selector
-            ui.label(egui::RichText::new("Y Axis:").size(15.0));
+            ui.label(egui::RichText::new("Y Axis:").size(font_15));
             egui::ComboBox::from_id_salt("histogram_y")
                 .selected_text(
                     egui::RichText::new(
@@ -189,7 +193,7 @@ impl UltraLogApp {
                             .and_then(|i| channel_names.get(&i).map(|n| n.as_str()))
                             .unwrap_or("Select..."),
                     )
-                    .size(14.0),
+                    .size(font_14),
                 )
                 .width(160.0)
                 .show_ui(ui, |ui| {
@@ -197,7 +201,7 @@ impl UltraLogApp {
                         if ui
                             .selectable_label(
                                 current_y == Some(*idx),
-                                egui::RichText::new(name).size(14.0),
+                                egui::RichText::new(name).size(font_14),
                             )
                             .clicked()
                         {
@@ -211,7 +215,7 @@ impl UltraLogApp {
             // Z Axis selector (only enabled in AverageZ mode)
             let z_enabled = current_mode == HistogramMode::AverageZ;
             ui.add_enabled_ui(z_enabled, |ui| {
-                ui.label(egui::RichText::new("Z Axis:").size(15.0));
+                ui.label(egui::RichText::new("Z Axis:").size(font_15));
                 egui::ComboBox::from_id_salt("histogram_z")
                     .selected_text(
                         egui::RichText::new(
@@ -219,7 +223,7 @@ impl UltraLogApp {
                                 .and_then(|i| channel_names.get(&i).map(|n| n.as_str()))
                                 .unwrap_or("Select..."),
                         )
-                        .size(14.0),
+                        .size(font_14),
                     )
                     .width(160.0)
                     .show_ui(ui, |ui| {
@@ -227,7 +231,7 @@ impl UltraLogApp {
                             if ui
                                 .selectable_label(
                                     current_z == Some(*idx),
-                                    egui::RichText::new(name).size(14.0),
+                                    egui::RichText::new(name).size(font_14),
                                 )
                                 .clicked()
                             {
@@ -240,9 +244,9 @@ impl UltraLogApp {
             ui.add_space(20.0);
 
             // Grid size selector
-            ui.label(egui::RichText::new("Grid:").size(15.0));
+            ui.label(egui::RichText::new("Grid:").size(font_15));
             egui::ComboBox::from_id_salt("histogram_grid_size")
-                .selected_text(egui::RichText::new(current_grid_size.name()).size(14.0))
+                .selected_text(egui::RichText::new(current_grid_size.name()).size(font_14))
                 .width(80.0)
                 .show_ui(ui, |ui| {
                     let sizes = [
@@ -254,7 +258,7 @@ impl UltraLogApp {
                         if ui
                             .selectable_label(
                                 current_grid_size == size,
-                                egui::RichText::new(size.name()).size(14.0),
+                                egui::RichText::new(size.name()).size(font_14),
                             )
                             .clicked()
                         {
@@ -266,11 +270,11 @@ impl UltraLogApp {
             ui.add_space(20.0);
 
             // Mode toggle
-            ui.label(egui::RichText::new("Mode:").size(15.0));
+            ui.label(egui::RichText::new("Mode:").size(font_15));
             if ui
                 .selectable_label(
                     current_mode == HistogramMode::AverageZ,
-                    egui::RichText::new("Average Z").size(14.0),
+                    egui::RichText::new("Average Z").size(font_14),
                 )
                 .clicked()
             {
@@ -279,7 +283,7 @@ impl UltraLogApp {
             if ui
                 .selectable_label(
                     current_mode == HistogramMode::HitCount,
-                    egui::RichText::new("Hit Count").size(14.0),
+                    egui::RichText::new("Hit Count").size(font_14),
                 )
                 .clicked()
             {
@@ -322,6 +326,12 @@ impl UltraLogApp {
         let mode = config.mode;
         let grid_size = config.grid_size.size();
 
+        // Pre-compute scaled font sizes for use in closures
+        let font_10 = self.scaled_font(10.0);
+        let font_12 = self.scaled_font(12.0);
+        let font_13 = self.scaled_font(13.0);
+        let font_16 = self.scaled_font(16.0);
+
         // Check valid axis selections
         let (x_idx, y_idx) = match (config.x_channel, config.y_channel) {
             (Some(x), Some(y)) => (x, y),
@@ -332,7 +342,7 @@ impl UltraLogApp {
                     rect.center(),
                     egui::Align2::CENTER_CENTER,
                     "Select X and Y axes",
-                    egui::FontId::proportional(16.0),
+                    egui::FontId::proportional(font_16),
                     egui::Color32::GRAY,
                 );
                 return;
@@ -350,7 +360,7 @@ impl UltraLogApp {
                         rect.center(),
                         egui::Align2::CENTER_CENTER,
                         "Select Z axis for Average mode",
-                        egui::FontId::proportional(16.0),
+                        egui::FontId::proportional(font_16),
                         egui::Color32::GRAY,
                     );
                     return;
@@ -499,19 +509,20 @@ impl UltraLogApp {
                         // Choose text color for AAA contrast compliance
                         let text_color = get_aaa_text_color(color);
 
-                        let font_size = if grid_size <= 16 {
+                        let base_font_size = if grid_size <= 16 {
                             11.0
                         } else if grid_size <= 32 {
                             9.0
                         } else {
                             7.0
                         };
+                        let cell_font_size = self.scaled_font(base_font_size);
 
                         painter.text(
                             cell_rect.center(),
                             egui::Align2::CENTER_CENTER,
                             text,
-                            egui::FontId::proportional(font_size),
+                            egui::FontId::proportional(cell_font_size),
                             text_color,
                         );
                     }
@@ -557,7 +568,7 @@ impl UltraLogApp {
                 egui::pos2(plot_rect.left() - 8.0, y_pos),
                 egui::Align2::RIGHT_CENTER,
                 format!("{:.1}", value),
-                egui::FontId::proportional(10.0),
+                egui::FontId::proportional(font_10),
                 text_color,
             );
         }
@@ -569,7 +580,7 @@ impl UltraLogApp {
             egui::pos2(y_title_x, y_title_y),
             egui::Align2::CENTER_CENTER,
             &y_channel_name,
-            egui::FontId::proportional(13.0),
+            egui::FontId::proportional(font_13),
             axis_title_color,
         );
 
@@ -582,7 +593,7 @@ impl UltraLogApp {
                 egui::pos2(x_pos, plot_rect.bottom() + 5.0),
                 egui::Align2::CENTER_TOP,
                 format!("{:.0}", value),
-                egui::FontId::proportional(10.0),
+                egui::FontId::proportional(font_10),
                 text_color,
             );
         }
@@ -594,7 +605,7 @@ impl UltraLogApp {
             egui::pos2(x_title_x, x_title_y),
             egui::Align2::CENTER_CENTER,
             &x_channel_name,
-            egui::FontId::proportional(13.0),
+            egui::FontId::proportional(font_13),
             axis_title_color,
         );
 
@@ -727,7 +738,7 @@ impl UltraLogApp {
                         egui::pos2(plot_rect.right() - 10.0, plot_rect.top() + 15.0),
                         egui::Align2::RIGHT_TOP,
                         tooltip_text,
-                        egui::FontId::proportional(12.0),
+                        egui::FontId::proportional(font_12),
                         egui::Color32::WHITE,
                     );
                 }
@@ -844,6 +855,8 @@ impl UltraLogApp {
         mode: HistogramMode,
         grid_size: usize,
     ) {
+        let font_13 = self.scaled_font(13.0);
+
         ui.horizontal(|ui| {
             ui.add_space(4.0);
 
@@ -860,7 +873,7 @@ impl UltraLogApp {
                         };
                         ui.label(
                             egui::RichText::new(label)
-                                .size(13.0)
+                                .size(font_13)
                                 .color(egui::Color32::WHITE),
                         );
 
@@ -894,7 +907,7 @@ impl UltraLogApp {
                         };
                         ui.label(
                             egui::RichText::new(range_text)
-                                .size(13.0)
+                                .size(font_13)
                                 .color(egui::Color32::WHITE),
                         );
                     });
@@ -911,13 +924,13 @@ impl UltraLogApp {
                     ui.horizontal(|ui| {
                         ui.label(
                             egui::RichText::new(format!("Grid: {}x{}", grid_size, grid_size))
-                                .size(13.0)
+                                .size(font_13)
                                 .color(egui::Color32::WHITE),
                         );
                         ui.add_space(12.0);
                         ui.label(
                             egui::RichText::new(format!("Total Points: {}", total_points))
-                                .size(13.0)
+                                .size(font_13)
                                 .color(egui::Color32::WHITE),
                         );
                     });
@@ -933,13 +946,18 @@ impl UltraLogApp {
 
         let selected = &self.tabs[tab_idx].histogram_state.config.selected_cell;
 
+        // Pre-compute scaled font sizes
+        let font_12 = self.scaled_font(12.0);
+        let font_13 = self.scaled_font(13.0);
+        let font_14 = self.scaled_font(14.0);
+
         ui.add_space(10.0);
         ui.separator();
         ui.add_space(5.0);
 
         ui.label(
             egui::RichText::new("Cell Statistics")
-                .size(14.0)
+                .size(font_14)
                 .strong()
                 .color(egui::Color32::WHITE),
         );
@@ -956,7 +974,7 @@ impl UltraLogApp {
                     ui.horizontal(|ui| {
                         ui.label(
                             egui::RichText::new(format!("Cell [{}, {}]", cell.x_bin, cell.y_bin))
-                                .size(13.0)
+                                .size(font_13)
                                 .color(SELECTED_CELL_COLOR),
                         );
                     });
@@ -985,7 +1003,7 @@ impl UltraLogApp {
                         ui.horizontal(|ui| {
                             ui.label(
                                 egui::RichText::new(format!("{}:", label))
-                                    .size(12.0)
+                                    .size(font_12)
                                     .color(egui::Color32::from_rgb(180, 180, 180)),
                             );
                             ui.with_layout(
@@ -993,7 +1011,7 @@ impl UltraLogApp {
                                 |ui| {
                                     ui.label(
                                         egui::RichText::new(&value)
-                                            .size(12.0)
+                                            .size(font_12)
                                             .color(egui::Color32::WHITE),
                                     );
                                 },
@@ -1010,7 +1028,7 @@ impl UltraLogApp {
         } else {
             ui.label(
                 egui::RichText::new("Click a cell to view statistics")
-                    .size(12.0)
+                    .size(font_12)
                     .italics()
                     .color(egui::Color32::GRAY),
             );
diff --git a/src/ui/menu.rs b/src/ui/menu.rs
index dd8e7f0..ab5bda3 100644
--- a/src/ui/menu.rs
+++ b/src/ui/menu.rs
@@ -4,7 +4,7 @@ use eframe::egui;
 
 use crate::analytics;
 use crate::app::UltraLogApp;
-use crate::state::{ActiveTool, LoadingState};
+use crate::state::{ActiveTool, FontScale, LoadingState};
 use crate::units::{
     AccelerationUnit, DistanceUnit, FlowUnit, FuelEconomyUnit, PressureUnit, SpeedUnit,
     TemperatureUnit, VolumeUnit,
@@ -13,11 +13,15 @@ use crate::units::{
 impl UltraLogApp {
     /// Render the application menu bar
     pub fn render_menu_bar(&mut self, ui: &mut egui::Ui) {
+        // Pre-compute scaled font sizes for use in closures
+        let font_14 = self.scaled_font(14.0);
+        let font_15 = self.scaled_font(15.0);
+
         egui::MenuBar::new().ui(ui, |ui| {
             // Increase font size for menu items
             ui.style_mut()
                 .text_styles
-                .insert(egui::TextStyle::Button, egui::FontId::proportional(15.0));
+                .insert(egui::TextStyle::Button, egui::FontId::proportional(font_15));
 
             // File menu
             ui.menu_button("File", |ui| {
@@ -26,10 +30,10 @@ impl UltraLogApp {
                 // Increase font size for dropdown items
                 ui.style_mut()
                     .text_styles
-                    .insert(egui::TextStyle::Button, egui::FontId::proportional(14.0));
+                    .insert(egui::TextStyle::Button, egui::FontId::proportional(font_14));
                 ui.style_mut()
                     .text_styles
-                    .insert(egui::TextStyle::Body, egui::FontId::proportional(14.0));
+                    .insert(egui::TextStyle::Body, egui::FontId::proportional(font_14));
 
                 let is_loading = matches!(self.loading_state, LoadingState::Loading(_));
 
@@ -68,7 +72,7 @@ impl UltraLogApp {
                         // Increase font size for submenu items
                         ui.style_mut()
                             .text_styles
-                            .insert(egui::TextStyle::Button, egui::FontId::proportional(14.0));
+                            .insert(egui::TextStyle::Button, egui::FontId::proportional(font_14));
 
                         if self.active_tool == ActiveTool::Histogram && has_histogram_data {
                             // Histogram export options
@@ -98,10 +102,10 @@ impl UltraLogApp {
                 // Increase font size for dropdown items
                 ui.style_mut()
                     .text_styles
-                    .insert(egui::TextStyle::Button, egui::FontId::proportional(14.0));
+                    .insert(egui::TextStyle::Button, egui::FontId::proportional(font_14));
                 ui.style_mut()
                     .text_styles
-                    .insert(egui::TextStyle::Body, egui::FontId::proportional(14.0));
+                    .insert(egui::TextStyle::Body, egui::FontId::proportional(font_14));
 
                 // Cursor Tracking toggle
                 if ui
@@ -153,6 +157,44 @@ impl UltraLogApp {
                 {
                     ui.close();
                 }
+
+                ui.separator();
+
+                // Font Size submenu
+                ui.menu_button("🔠  Font Size", |ui| {
+                    ui.style_mut()
+                        .text_styles
+                        .insert(egui::TextStyle::Button, egui::FontId::proportional(font_14));
+
+                    if ui
+                        .radio_value(&mut self.font_scale, FontScale::Small, "Small (85%)")
+                        .clicked()
+                    {
+                        ui.close();
+                    }
+                    if ui
+                        .radio_value(&mut self.font_scale, FontScale::Medium, "Medium (100%)")
+                        .clicked()
+                    {
+                        ui.close();
+                    }
+                    if ui
+                        .radio_value(&mut self.font_scale, FontScale::Large, "Large (120%)")
+                        .clicked()
+                    {
+                        ui.close();
+                    }
+                    if ui
+                        .radio_value(
+                            &mut self.font_scale,
+                            FontScale::ExtraLarge,
+                            "Extra Large (140%)",
+                        )
+                        .clicked()
+                    {
+                        ui.close();
+                    }
+                });
             });
 
             // Units menu
@@ -162,17 +204,17 @@ impl UltraLogApp {
                 // Increase font size for dropdown items
                 ui.style_mut()
                     .text_styles
-                    .insert(egui::TextStyle::Button, egui::FontId::proportional(14.0));
+                    .insert(egui::TextStyle::Button, egui::FontId::proportional(font_14));
                 ui.style_mut()
                     .text_styles
-                    .insert(egui::TextStyle::Body, egui::FontId::proportional(14.0));
+                    .insert(egui::TextStyle::Body, egui::FontId::proportional(font_14));
 
                 // Temperature submenu
                 ui.menu_button("°C  Temperature", |ui| {
                     // Increase font size for submenu items
                     ui.style_mut()
                         .text_styles
-                        .insert(egui::TextStyle::Button, egui::FontId::proportional(14.0));
+                        .insert(egui::TextStyle::Button, egui::FontId::proportional(font_14));
                     if ui
                         .radio_value(
                             &mut self.unit_preferences.temperature,
@@ -210,7 +252,7 @@ impl UltraLogApp {
                     // Increase font size for submenu items
                     ui.style_mut()
                         .text_styles
-                        .insert(egui::TextStyle::Button, egui::FontId::proportional(14.0));
+                        .insert(egui::TextStyle::Button, egui::FontId::proportional(font_14));
                     if ui
                         .radio_value(
                             &mut self.unit_preferences.pressure,
@@ -248,7 +290,7 @@ impl UltraLogApp {
                     // Increase font size for submenu items
                     ui.style_mut()
                         .text_styles
-                        .insert(egui::TextStyle::Button, egui::FontId::proportional(14.0));
+                        .insert(egui::TextStyle::Button, egui::FontId::proportional(font_14));
                     if ui
                         .radio_value(
                             &mut self.unit_preferences.speed,
@@ -276,7 +318,7 @@ impl UltraLogApp {
                     // Increase font size for submenu items
                     ui.style_mut()
                         .text_styles
-                        .insert(egui::TextStyle::Button, egui::FontId::proportional(14.0));
+                        .insert(egui::TextStyle::Button, egui::FontId::proportional(font_14));
                     if ui
                         .radio_value(
                             &mut self.unit_preferences.distance,
@@ -306,7 +348,7 @@ impl UltraLogApp {
                     // Increase font size for submenu items
                     ui.style_mut()
                         .text_styles
-                        .insert(egui::TextStyle::Button, egui::FontId::proportional(14.0));
+                        .insert(egui::TextStyle::Button, egui::FontId::proportional(font_14));
                     if ui
                         .radio_value(
                             &mut self.unit_preferences.fuel_economy,
@@ -344,7 +386,7 @@ impl UltraLogApp {
                     // Increase font size for submenu items
                     ui.style_mut()
                         .text_styles
-                        .insert(egui::TextStyle::Button, egui::FontId::proportional(14.0));
+                        .insert(egui::TextStyle::Button, egui::FontId::proportional(font_14));
                     if ui
                         .radio_value(
                             &mut self.unit_preferences.volume,
@@ -372,7 +414,7 @@ impl UltraLogApp {
                     // Increase font size for submenu items
                     ui.style_mut()
                         .text_styles
-                        .insert(egui::TextStyle::Button, egui::FontId::proportional(14.0));
+                        .insert(egui::TextStyle::Button, egui::FontId::proportional(font_14));
                     if ui
                         .radio_value(
                             &mut self.unit_preferences.flow,
@@ -398,7 +440,7 @@ impl UltraLogApp {
                     // Increase font size for submenu items
                     ui.style_mut()
                         .text_styles
-                        .insert(egui::TextStyle::Button, egui::FontId::proportional(14.0));
+                        .insert(egui::TextStyle::Button, egui::FontId::proportional(font_14));
                     if ui
                         .radio_value(
                             &mut self.unit_preferences.acceleration,
@@ -429,10 +471,10 @@ impl UltraLogApp {
                 // Increase font size for dropdown items
                 ui.style_mut()
                     .text_styles
-                    .insert(egui::TextStyle::Button, egui::FontId::proportional(14.0));
+                    .insert(egui::TextStyle::Button, egui::FontId::proportional(font_14));
                 ui.style_mut()
                     .text_styles
-                    .insert(egui::TextStyle::Body, egui::FontId::proportional(14.0));
+                    .insert(egui::TextStyle::Body, egui::FontId::proportional(font_14));
 
                 if ui.button("ƒ(x)  Computed Channels...").clicked() {
                     self.show_computed_channels_manager = true;
@@ -453,10 +495,10 @@ impl UltraLogApp {
                 // Increase font size for dropdown items
                 ui.style_mut()
                     .text_styles
-                    .insert(egui::TextStyle::Button, egui::FontId::proportional(14.0));
+                    .insert(egui::TextStyle::Button, egui::FontId::proportional(font_14));
                 ui.style_mut()
                     .text_styles
-                    .insert(egui::TextStyle::Body, egui::FontId::proportional(14.0));
+                    .insert(egui::TextStyle::Body, egui::FontId::proportional(font_14));
 
                 if ui.button("📖  Documentation").clicked() {
                     let _ = open::that("https://github.com/SomethingNew71/UltraLog/wiki");
diff --git a/src/ui/scatter_plot.rs b/src/ui/scatter_plot.rs
index f06f3c4..0e425c2 100644
--- a/src/ui/scatter_plot.rs
+++ b/src/ui/scatter_plot.rs
@@ -45,7 +45,7 @@ impl UltraLogApp {
             ui.centered_and_justified(|ui| {
                 ui.label(
                     egui::RichText::new("Load a log file to use scatter plots")
-                        .size(20.0)
+                        .size(self.scaled_font(20.0))
                         .color(egui::Color32::GRAY),
                 );
             });
@@ -95,7 +95,7 @@ impl UltraLogApp {
         ui.horizontal(|ui| {
             ui.label(
                 egui::RichText::new(&title)
-                    .size(16.0)
+                    .size(self.scaled_font(16.0))
                     .strong()
                     .color(egui::Color32::WHITE),
             );
@@ -266,6 +266,11 @@ impl UltraLogApp {
 
         let file_idx = config.file_index.unwrap_or(self.tabs[tab_idx].file_index);
 
+        // Pre-compute scaled font sizes
+        let font_10 = self.scaled_font(10.0);
+        let font_11 = self.scaled_font(11.0);
+        let font_16 = self.scaled_font(16.0);
+
         // Check if we have valid axis selections
         let (x_idx, y_idx) = match (config.x_channel, config.y_channel) {
             (Some(x), Some(y)) => (x, y),
@@ -277,7 +282,7 @@ impl UltraLogApp {
                     rect.center(),
                     egui::Align2::CENTER_CENTER,
                     "Select X and Y axes",
-                    egui::FontId::proportional(16.0),
+                    egui::FontId::proportional(font_16),
                     egui::Color32::GRAY,
                 );
                 return;
@@ -396,7 +401,7 @@ impl UltraLogApp {
                 egui::pos2(plot_rect.left() - 5.0, y_pos),
                 egui::Align2::RIGHT_CENTER,
                 format!("{:.1}", value),
-                egui::FontId::proportional(10.0),
+                egui::FontId::proportional(font_10),
                 text_color,
             );
 
@@ -421,7 +426,7 @@ impl UltraLogApp {
                 egui::pos2(x_pos, plot_rect.bottom() + 5.0),
                 egui::Align2::CENTER_TOP,
                 format!("{:.0}", value),
-                egui::FontId::proportional(10.0),
+                egui::FontId::proportional(font_10),
                 text_color,
             );
 
@@ -510,7 +515,7 @@ impl UltraLogApp {
                         egui::pos2(plot_rect.right() - 10.0, plot_rect.top() + 15.0),
                         egui::Align2::RIGHT_TOP,
                         tooltip_text,
-                        egui::FontId::proportional(11.0),
+                        egui::FontId::proportional(font_11),
                         egui::Color32::WHITE,
                     );
 
@@ -571,6 +576,10 @@ impl UltraLogApp {
             return;
         };
 
+        // Pre-compute scaled font sizes
+        let font_10 = self.scaled_font(10.0);
+        let font_11 = self.scaled_font(11.0);
+
         // First, gather the data we need (immutable borrow)
         let config = if is_left {
             &self.tabs[tab_idx].scatter_plot_state.left
@@ -631,7 +640,7 @@ impl UltraLogApp {
                     ui.horizontal(|ui| {
                         ui.label(
                             egui::RichText::new("Hits:")
-                                .size(11.0)
+                                .size(font_11)
                                 .color(egui::Color32::WHITE),
                         );
 
@@ -660,7 +669,7 @@ impl UltraLogApp {
                         ui.add_space(4.0);
                         ui.label(
                             egui::RichText::new(format!("0-{}", max_hits))
-                                .size(10.0)
+                                .size(font_10)
                                 .color(egui::Color32::WHITE),
                         );
                     });
@@ -697,7 +706,7 @@ impl UltraLogApp {
                                     selected.y_value,
                                     selected.hits
                                 ))
-                                .size(11.0)
+                                .size(font_11)
                                 .color(egui::Color32::WHITE),
                             );
 
diff --git a/src/ui/sidebar.rs b/src/ui/sidebar.rs
index dea7f2d..82a553a 100644
--- a/src/ui/sidebar.rs
+++ b/src/ui/sidebar.rs
@@ -66,7 +66,7 @@ impl UltraLogApp {
                             "{} | {} channels | {} points",
                             ecu_name, channel_count, data_count
                         ))
-                        .size(12.0)
+                        .size(self.scaled_font(12.0))
                         .color(egui::Color32::GRAY),
                     );
                 });
@@ -98,7 +98,7 @@ impl UltraLogApp {
                             ui.label(
                                 egui::RichText::new("+ Add File")
                                     .color(egui::Color32::WHITE)
-                                    .size(14.0),
+                                    .size(self.scaled_font(14.0)),
                             );
                         });
 
@@ -163,7 +163,7 @@ impl UltraLogApp {
                             ui.label(
                                 egui::RichText::new("Select a file")
                                     .color(egui::Color32::WHITE)
-                                    .size(14.0),
+                                    .size(self.scaled_font(14.0)),
                             );
                         });
 
@@ -186,14 +186,18 @@ impl UltraLogApp {
 
                     ui.add_space(12.0);
 
-                    ui.label(egui::RichText::new("or").color(text_gray).size(12.0));
+                    ui.label(
+                        egui::RichText::new("or")
+                            .color(text_gray)
+                            .size(self.scaled_font(12.0)),
+                    );
 
                     ui.add_space(8.0);
 
                     ui.label(
                         egui::RichText::new("Drop file here")
                             .color(egui::Color32::LIGHT_GRAY)
-                            .size(13.0),
+                            .size(self.scaled_font(13.0)),
                     );
 
                     ui.add_space(12.0);
@@ -201,7 +205,7 @@ impl UltraLogApp {
                     ui.label(
                         egui::RichText::new("CSV • LOG • TXT • MLG")
                             .color(text_gray)
-                            .size(11.0),
+                            .size(self.scaled_font(11.0)),
                     );
                 });
             });
@@ -209,6 +213,11 @@ impl UltraLogApp {
 
     /// Render view options at the bottom of the sidebar
     fn render_view_options(&mut self, ui: &mut egui::Ui) {
+        // Pre-compute scaled font sizes
+        let font_12 = self.scaled_font(12.0);
+        let font_14 = self.scaled_font(14.0);
+        let font_18 = self.scaled_font(18.0);
+
         ui.with_layout(egui::Layout::bottom_up(egui::Align::LEFT), |ui| {
             // Reverse order since we're bottom-up
             ui.add_space(10.0);
@@ -232,16 +241,20 @@ impl UltraLogApp {
                     .inner_margin(10.0)
                     .show(ui, |ui| {
                         // Cursor tracking checkbox
-                        ui.checkbox(&mut self.cursor_tracking, "🎯  Cursor Tracking");
+                        ui.checkbox(
+                            &mut self.cursor_tracking,
+                            egui::RichText::new("🎯  Cursor Tracking").size(font_14),
+                        );
                         ui.label(
                             egui::RichText::new("Keep cursor centered while scrubbing")
-                                .color(egui::Color32::GRAY),
+                                .color(egui::Color32::GRAY)
+                                .size(font_12),
                         );
 
                         // Window size slider (only show when cursor tracking is enabled)
                         if self.cursor_tracking {
                             ui.add_space(8.0);
-                            ui.label("View Window:");
+                            ui.label(egui::RichText::new("View Window:").size(font_14));
                             ui.add(
                                 egui::Slider::new(&mut self.view_window_seconds, 5.0..=120.0)
                                     .suffix("s")
@@ -254,10 +267,14 @@ impl UltraLogApp {
                         ui.add_space(4.0);
 
                         // Color blind mode checkbox
-                        ui.checkbox(&mut self.color_blind_mode, "👁  Color Blind Mode");
+                        ui.checkbox(
+                            &mut self.color_blind_mode,
+                            egui::RichText::new("👁  Color Blind Mode").size(font_14),
+                        );
                         ui.label(
                             egui::RichText::new("Use accessible color palette")
-                                .color(egui::Color32::GRAY),
+                                .color(egui::Color32::GRAY)
+                                .size(font_12),
                         );
 
                         ui.add_space(8.0);
@@ -266,7 +283,10 @@ impl UltraLogApp {
 
                         // Field normalization checkbox with right-aligned Edit button
                         ui.horizontal(|ui| {
-                            ui.checkbox(&mut self.field_normalization, "📝  Field Normalization");
+                            ui.checkbox(
+                                &mut self.field_normalization,
+                                egui::RichText::new("📝  Field Normalization").size(font_14),
+                            );
                             ui.with_layout(
                                 egui::Layout::right_to_left(egui::Align::Center),
                                 |ui| {
@@ -278,13 +298,14 @@ impl UltraLogApp {
                         });
                         ui.label(
                             egui::RichText::new("Standardize channel names across ECU types")
-                                .color(egui::Color32::GRAY),
+                                .color(egui::Color32::GRAY)
+                                .size(font_12),
                         );
                     });
 
                 ui.add_space(5.0);
                 ui.separator();
-                ui.heading("View Options");
+                ui.label(egui::RichText::new("View Options").heading().size(font_18));
             }
         });
     }
diff --git a/src/ui/tab_bar.rs b/src/ui/tab_bar.rs
index a507880..98c27a3 100644
--- a/src/ui/tab_bar.rs
+++ b/src/ui/tab_bar.rs
@@ -63,9 +63,10 @@ impl UltraLogApp {
                     .show(ui, |ui| {
                         ui.horizontal(|ui| {
                             // Tab name (clickable)
+                            let font_13 = self.scaled_font(13.0);
                             let label_response = ui.add(
                                 egui::Label::new(
-                                    egui::RichText::new(name).color(text_color).size(13.0),
+                                    egui::RichText::new(name).color(text_color).size(font_13),
                                 )
                                 .sense(egui::Sense::click()),
                             );
@@ -80,11 +81,12 @@ impl UltraLogApp {
                             ui.add_space(4.0);
 
                             // Close button
+                            let font_14 = self.scaled_font(14.0);
                             let close_btn = ui.add(
                                 egui::Label::new(
                                     egui::RichText::new("×")
                                         .color(egui::Color32::from_rgb(150, 150, 150))
-                                        .size(14.0),
+                                        .size(font_14),
                                 )
                                 .sense(egui::Sense::click()),
                             );
diff --git a/src/ui/timeline.rs b/src/ui/timeline.rs
index 03051ba..dae566e 100644
--- a/src/ui/timeline.rs
+++ b/src/ui/timeline.rs
@@ -8,6 +8,9 @@ use crate::app::UltraLogApp;
 impl UltraLogApp {
     /// Render the timeline scrubber bar
     pub fn render_timeline_scrubber(&mut self, ui: &mut egui::Ui) {
+        // Pre-compute scaled font size
+        let font_12 = self.scaled_font(12.0);
+
         let Some((min_time, max_time)) = self.get_time_range() else {
             return;
         };
@@ -20,12 +23,15 @@ impl UltraLogApp {
         // Time labels row
         ui.horizontal(|ui| {
             ui.label(
-                egui::RichText::new(Self::format_time(min_time)).color(egui::Color32::LIGHT_GRAY),
+                egui::RichText::new(Self::format_time(min_time))
+                    .color(egui::Color32::LIGHT_GRAY)
+                    .size(font_12),
             );
             ui.with_layout(egui::Layout::right_to_left(egui::Align::Center), |ui| {
                 ui.label(
                     egui::RichText::new(Self::format_time(max_time))
-                        .color(egui::Color32::LIGHT_GRAY),
+                        .color(egui::Color32::LIGHT_GRAY)
+                        .size(font_12),
                 );
             });
         });
@@ -63,19 +69,24 @@ impl UltraLogApp {
 
     /// Render the record/time indicator bar with playback controls
     pub fn render_record_indicator(&mut self, ui: &mut egui::Ui) {
+        // Pre-compute scaled font size
+        let font_14 = self.scaled_font(14.0);
+
         ui.horizontal(|ui| {
             // Playback controls
             let button_size = egui::vec2(28.0, 28.0);
 
             // Play/Pause button
             let play_text = if self.is_playing { "⏸" } else { "▶" };
-            let play_button = egui::Button::new(egui::RichText::new(play_text).size(16.0).color(
-                if self.is_playing {
-                    egui::Color32::from_rgb(253, 193, 73) // Amber when playing
-                } else {
-                    egui::Color32::from_rgb(144, 238, 144) // Light green when paused
-                },
-            ))
+            let play_button = egui::Button::new(
+                egui::RichText::new(play_text)
+                    .size(self.scaled_font(16.0))
+                    .color(if self.is_playing {
+                        egui::Color32::from_rgb(253, 193, 73) // Amber when playing
+                    } else {
+                        egui::Color32::from_rgb(144, 238, 144) // Light green when paused
+                    }),
+            )
             .min_size(button_size);
 
             if ui.add(play_button).clicked() {
@@ -99,7 +110,7 @@ impl UltraLogApp {
             // Stop button (resets to beginning)
             let stop_button = egui::Button::new(
                 egui::RichText::new("⏹")
-                    .size(16.0)
+                    .size(self.scaled_font(16.0))
                     .color(egui::Color32::from_rgb(191, 78, 48)), // Rust orange
             )
             .min_size(button_size);
@@ -118,7 +129,11 @@ impl UltraLogApp {
             ui.separator();
 
             // Playback speed selector
-            ui.label(egui::RichText::new("Speed:").color(egui::Color32::GRAY));
+            ui.label(
+                egui::RichText::new("Speed:")
+                    .color(egui::Color32::GRAY)
+                    .size(font_14),
+            );
 
             let speed_options = [0.25, 0.5, 1.0, 2.0, 4.0, 8.0];
             egui::ComboBox::from_id_salt("playback_speed")
@@ -137,7 +152,8 @@ impl UltraLogApp {
                 ui.label(
                     egui::RichText::new(format!("Time: {}", Self::format_time(time)))
                         .strong()
-                        .color(egui::Color32::from_rgb(0, 255, 255)), // Cyan to match cursor
+                        .color(egui::Color32::from_rgb(0, 255, 255)) // Cyan to match cursor
+                        .size(font_14),
                 );
             }
 
@@ -155,7 +171,8 @@ impl UltraLogApp {
                                 record + 1,
                                 total_records
                             ))
-                            .color(egui::Color32::LIGHT_GRAY),
+                            .color(egui::Color32::LIGHT_GRAY)
+                            .size(font_14),
                         );
                     }
                 }
diff --git a/src/ui/toast.rs b/src/ui/toast.rs
index a52f0c3..c0472d9 100644
--- a/src/ui/toast.rs
+++ b/src/ui/toast.rs
@@ -44,7 +44,7 @@ impl UltraLogApp {
                                             text_color[1],
                                             text_color[2],
                                         ))
-                                        .size(14.0),
+                                        .size(self.scaled_font(14.0)),
                                 );
                             });
                     });
diff --git a/src/ui/tool_switcher.rs b/src/ui/tool_switcher.rs
index 90493f7..b036b55 100644
--- a/src/ui/tool_switcher.rs
+++ b/src/ui/tool_switcher.rs
@@ -48,7 +48,7 @@ impl UltraLogApp {
                 let response = ui.add(
                     egui::Button::new(
                         egui::RichText::new(tool.name())
-                            .size(14.0)
+                            .size(self.scaled_font(14.0))
                             .color(text_color),
                     )
                     .fill(button_fill)
diff --git a/src/ui/update_dialog.rs b/src/ui/update_dialog.rs
index 23ee10d..4d14faa 100644
--- a/src/ui/update_dialog.rs
+++ b/src/ui/update_dialog.rs
@@ -63,7 +63,7 @@ impl UltraLogApp {
 
             ui.label(
                 egui::RichText::new("A new version is available!")
-                    .size(18.0)
+                    .size(self.scaled_font(18.0))
                     .strong(),
             );
 
@@ -133,7 +133,7 @@ impl UltraLogApp {
         ui.vertical_centered(|ui| {
             ui.add_space(20.0);
 
-            ui.label(egui::RichText::new("Downloading update...").size(16.0));
+            ui.label(egui::RichText::new("Downloading update...").size(self.scaled_font(16.0)));
 
             ui.add_space(15.0);
 
@@ -158,7 +158,7 @@ impl UltraLogApp {
 
             ui.label(
                 egui::RichText::new("Download complete!")
-                    .size(16.0)
+                    .size(self.scaled_font(16.0))
                     .color(egui::Color32::LIGHT_GREEN),
             );
 
@@ -224,7 +224,7 @@ impl UltraLogApp {
 
             ui.label(
                 egui::RichText::new("Update Error")
-                    .size(16.0)
+                    .size(self.scaled_font(16.0))
                     .color(egui::Color32::from_rgb(191, 78, 48)),
             );