Question 1

How do I test a QR code before printing?

Accepted Answer

Check six things on the exact file you are about to export: contrast ratio, polarity, the four-module quiet zone, the minimum print size for your module count, payload headroom against capacity, and logo coverage against the error-correction level. Then print one physical proof at final size on the final substrate and scan it with two different phones.

Question 2

What is the minimum size for a QR code?

Accepted Answer

There is no single figure, because the minimum depends on how many modules your code has, which depends on how much data you encoded. A code with a short payload can print far smaller than one carrying a long tracking URL.

Question 3

Why won't my QR code scan?

Accepted Answer

The common causes, in order: not enough contrast, a cropped or missing quiet zone, printed too small for the module count, inverted polarity, or a logo covering more of the pattern than error correction can rebuild. If the code is recognised but nothing loads, the problem is the destination or the redirect rather than the print.

Question 4

What contrast ratio does a QR code need?

Accepted Answer

Roughly 4:1 or better between the modules and their background for reliable scanning on paper. Anything lower depends on the phone, the light and the printing, and will work for some readers and not others.

Question 5

How big does the quiet zone need to be?

Accepted Answer

Four modules on every side. That is the ISO/IEC 18004 minimum, and it is the margin scanners use to locate the pattern. Never crop it to make a code fit; shrink the code instead.

Question 6

Can I put a logo in the middle of a QR code?

Accepted Answer

Yes, within the error-correction budget. Level L recovers about 7% of the code, M about 15%, Q about 25% and H about 30%. A logo that overlaps more of the pattern than the level can recover will fail unpredictably, which is worse than failing outright.

Question 7

Does this send my code or my design anywhere?

Accepted Answer

No. The checks are computed in your browser from the design you are editing. Nothing is stored until you choose to save a code, which requires an account.

QR Code Scan Test — Check It Before You Print