Calibrate your 3D printer's X, Y and Z scale and skew (the XY, XZ and YZ planes) by scanning printed coupons on an ordinary office scanner. No calipers, no measuring, no typing numbers into a calculator.
The result is a ready-to-paste correction for your firmware or slicer, worked out from a flat scan of a printed coupon.
Runs entirely in your browser. Nothing to install, nothing uploaded to a server, on desktop or phone.
Tip
A regular office flatbed scanner is all you need. The same kind you'd use to copy a document, including the scanner built into an all-in-one printer. No camera photos, no special hardware, and no high end machine required. Scan at 600 DPI, which any normal home or office scanner can do.
Warning
XY calibration is solid. XZ and YZ are experimental: the standing-plate scans work, but the correction math for those planes hasn't seen the same real-world validation as XY yet. Sanity-check the results before trusting them on your printer.
- Once per scanner: scan any plastic card (a credit, debit or loyalty card) so ScanNTune learns your scanner's true scale.
- Print the plate(s): one plate per plane you want to check. XY prints flat; XZ and YZ print standing on-edge. Print only the planes you care about.
- Scan each twice: lay a plate on the scanner and scan it flat, then give it a quarter turn and scan it again. Repeat for any other plates.
- Drop them all in: open every scan in ScanNTune at once. It sorts them by plate automatically and gives you the firmware or slicer snippet for X/Y/Z scale and skew.
That's it. The whole thing takes a couple of minutes once the plates are printed.
I built this because I got tired of dimensional calibration. The usual routine is a printed coupon and a matching calculator, like Vector 3D's "Califlower": print it, measure it corner to corner with calipers, measure the diagonals for skew, type all of that into the calculator, and paste the result into your firmware. The measuring is the annoying part: several caliper readings to take and keep track of, a diagonal for skew that's awkward to measure squarely, and then all of it typed into the calculator without a mistake. So I let a scanner do the reading instead.
Here's the same printer measured both ways: ScanNTune's result (left) and Califlower's coupon hand-measured into its calculator (right).
The two come out almost exactly the same, differing by only 0.05% in X, 0.08% in Y, and 0.03° in skew. They should match, because both are measuring the same printer. The only difference is that ScanNTune reads it from a single scan instead of by hand with a caliper.
- Extrusion width doesn't affect it. The coupon is a lattice of rings, and a ring's centre doesn't move when the walls print fatter or thinner. Over- or under-extrusion can't shift the scale or skew.
- Two scans remove the scanner's distortion. A flatbed scanner has its own slight stretch and skew. Scanning the coupon flat, then again quarter-turned, and averaging the two cancels the scanner's error and leaves the printer's. The leftover half-difference even tells you how far off your scanner is.
- It calibrates scale off a plastic card. A scanner's stated DPI is rarely exact, so ScanNTune measures a standard plastic card instead (all cards are ISO/IEC 7810 ID-1, 85.60 by 53.98 mm) and reads the true pixels-per-millimetre from its edges.
The computer vision runs client-side in a Web Worker with OpenCV.js, so a full scan is analysed on your own machine without the page ever freezing.
The app is a plain Vue 3 + TypeScript + Vite project under
web/. You'll need Node.js 22 or newer.
cd web
npm install
npm run dev # dev server at http://localhost:5173/
npm run build # production build to web/dist
npm test # Vitest unit + fixture-backed engine tests
npm run e2e # Playwright end-to-end over real scansWant a different coupon size or grid? Edit calibration_coupon.scad in OpenSCAD
and export your own STL.
MIT © 2026 Jakob Eichberger