How to check a QR code
- Export the code exactly as it will be printed: the final PNG, SVG or a screenshot of your finished design (menu, poster, label), not just the bare code.
- Upload the file, drag it onto the box, or copy it and press Ctrl/Cmd + V on this page.
- Optionally type the width you plan to print the code at. The checker estimates the module size on paper and a comfortable scanning distance.
- Read the verdict, then go through any yellow or red items. Each one says what to change.
- Fix the design, check it again, and finish with a real test: print one copy at full size and scan it with two different phones.
What each check means
- Contrast
- Compares the brightness of dark and light modules. Below about 3.5 : 1, phones start to miss modules in dim light. Inverted codes (light on dark) are flagged because some older scanners cannot read them.
- Quiet zone
- The blank margin around the code. The QR standard asks for 4 modules on every side. Cropped codes, or codes touching text and photos, are the most common print mistake.
- Data density
- The QR version, from 1 (21 × 21 modules) to 40 (177 × 177). Higher versions pack in more data but need a bigger, sharper print.
- Image resolution
- How many pixels each module uses in your file. Under 3 px looks blurry when enlarged. For print, SVG avoids the problem completely.
- Small / distant scan test
- The image is shrunk until each module is about 2.5 px, roughly what a phone camera sees from across a table, and decoded again.
- Content
- Shows what the code really contains and warns about plain http links and link shorteners that can expire.
When to run a check
Before a print order
Menus, packaging, flyers and stickers are expensive to reprint. A two-minute check catches cropped margins and low contrast first.
After a designer has styled the code
Brand colors, gradients, rounded dots and logos all change how readable a code is. Check the final artwork, not the original download.
When a printed code is not scanning
Take a straight, sharp photo of the printed code and upload it. The report usually points to the cause.
Codes made with other tools
The checker works with any QR code image, including codes from payment apps, other generators and supplier labels.
How the verdict is decided
Every check is marked green, yellow or red. The overall verdict is the worst of them: one red item means the code is likely to fail on some phones, even if everything else is fine.
The thresholds are deliberately cautious. A code with a yellow item often scans on a new phone in good light, but the people scanning your code may have older phones, cracked lenses or be standing in a dim corridor.
| Check | Green | Yellow | Red |
|---|---|---|---|
| Contrast | 7 : 1 or more | 3.5 – 7 : 1, or inverted | Under 3.5 : 1 |
| Quiet zone | 3.5+ modules, clean | Thin or busy margin | Cropped, or only reads with added margin |
| Data density | Version 1–6 | Version 7–10 | Version 11+ |
| Resolution | 8+ px per module | 3–8 px | Under 3 px |
What the checker cannot tell you
- It tests an image, not paper. Glossy lamination, curved surfaces, ink spread and lighting can still cause problems, so always scan a real printed sample.
- It reads QR codes only. For barcodes (EAN, UPC, Code 128), use the scanner page.
- It does not open or verify the link. It shows the domain so you can judge it yourself.
- Photos taken at a steep angle can give a rough module size. For the most accurate report, upload the original file.
Questions people ask
Is my image uploaded?
No. The image is decoded and measured in your browser. Nothing is sent to a server.
My code gets a red mark but my phone scans it. Is the checker wrong?
Your phone in your light is the best case. The checks look for margins that fail on older phones, at a distance or in dim places. Fixing them makes the code work for more people.
Can it check a code with a logo?
Yes. A logo lowers the effective contrast and covers modules, so codes with logos are a good reason to run the small-size test.
Last updated 23 October 2026 by the QRizeo team.