Free tools · Measured, not looked up
How big does that QR code need to print?
Most size charts guess from averages. This one encodes your actual content, counts the real grid, and applies the two rules that govern print — the 10:1 distance rule and the half-millimetre module floor. Type what the code will carry, pick how far people scan from, read the number.
Furthest someone will scan from
Error correction
Minimum print size
15.0 cm per side
- Grid (with quiet zone)
- 25 + 8 = 33 modules
- Module size at minimum
- 4.55 mm
Bounded by the 10:1 distance rule. Print smaller than this and scans start failing before people get close enough.
Why we obsess over one character
The boundary that decides your scan distance
QR grids grow in steps: cross a data threshold by a single character and the whole code jumps to the next version — more, smaller modules at the same print size. Our own short URLs are 26 characters because 27 would tip the grid from 25 to 29 modules per side: one character costs 14% of every module's printed size, on every code, forever. Play with the calculator and you can watch the cliff happen.
https://go.qr-m.in/aB3xY9z
26 chars → 25×25 modules ✓
https://link.example/aB3xY9z
28 chars → 29×29 modules — every module 14% smaller
Questions
How big should a QR code be printed?
Two rules together give the answer: a code scans reliably to about ten times its printed width (so divide the scan distance by ten), and a printed module below about half a millimetre dissolves into ink spread. The calculator applies both to your actual content and takes the larger answer.
Why does what I encode change the size?
Every character adds modules to the grid, and each module needs physical size to survive printing and distance. A 26-character URL fits a 25-module grid; a long vCard can need twice that — at the same print size its modules are half as big, so it must print larger to scan as well.
Does error correction change the answer?
Yes — higher error correction stores more redundancy, which can push the grid to a larger version with more, smaller modules. Use standard (M) without a logo; with a logo, high (H) is non-negotiable, and the calculator shows what it costs in size.
Already have a code to check? The scannability checker stress-tests any image. Making a new one? The free generators draw decode-verified codes for every type.
Short URLs are a print feature
Dynamic codes here carry a 26-character URL on purpose — the largest modules a shortened link can print. Repointable forever, on your domain if you want it.