How to Test a QR Code
A repeatable routine to run before a print order, so a five-minute check does not become a five-thousand-unit reprint.
On this page
Why on-screen testing is not testing
A screen is backlit, perfectly sharp and perfectly contrasted. Paper is none of those. Every real failure — bleed, low contrast on stock, a lost quiet zone, a code printed smaller than intended — appears between the file and the finished object. Test the object.
Step 1: verify the file
In the generator, press Verify scan. The image you are about to download is re-decoded in your browser and compared against your data character by character. If that fails, nothing later can succeed. This step costs a second and eliminates a whole class of problems.
Step 2: read the scan check
The panel beside the preview rates contrast, quiet zone, density, logo coverage and export resolution as Good, Needs attention or High risk, with the reason and the fix. Clear everything down to Good before you export. "Needs attention" items are not fatal, but each one is a margin you are spending in advance.
Step 3: print a real sample
Final size, final material, final printer. A proof on office paper tells you almost nothing about how the code will behave on matte board, foil or corrugated card. If the run is large enough to matter, get a press proof.
Step 4: scan it like a customer would
- Three or more phones, including the oldest one in the office.
- The native camera app, not a specialist scanner app — that is what people use.
- At the distance and angle the real placement forces.
- In the actual lighting: dim restaurant, fluorescent warehouse, direct sun.
- Both landscape and portrait, and at about 30° off-axis.
Record how long each scan takes. Anything that needs more than about two seconds of hunting will be abandoned in the wild.
Step 5: confirm the destination
Read the URL your phone shows before opening it. Check it is the right page, that it loads on mobile data rather than only on office Wi-Fi, and that it is not a staging URL. Then check it again the day the material ships.
Step 6: keep the artwork
Save the SVG and the settings you used. Reprints months later that "look the same" but were regenerated with different options are a recurring source of mystery failures.
A pass/fail bar worth adopting
| Check | Pass |
|---|---|
| Verify scan | Decoded, content matches exactly |
| Contrast ratio | 7:1 or better |
| Quiet zone | 4 modules on all four sides |
| Printed width | At least 20 mm, and ≥ distance ÷ 10 |
| Devices tested | 3 or more, including one 3+ years old |
| Time to scan | Under 2 seconds each time |
Sources
Symbol structure and quiet-zone requirements: ISO/IEC 18004. Formal print-quality grading for 2-D symbols, if your supply chain requires it: ISO/IEC 15415.