Check a QR code before printing
Make sure phones read your code before you print the whole run.
Check your code's image as it will be printed
We read it in your browser and measure what matters to the printer.
The picture is read in your browser, and is not uploaded to us or kept.
We could not read a code in this picture. If it is clear and shows the whole code, many phones will probably not read it either: do not print it as it is.
The reader could not be loaded. Reload the page and try again.
- Whether it scans, and what it opens
- The contrast between the squares and the background
- The margin around it and the picture's sharpness
- The smallest size to print it at
Reading the picture…
It scans, and this is what it opens
A web link A Wi-Fi network's details A contact card A number, a message or a place on the map Text
The site it opens:
- This link is not encrypted (http). Do not type a password or card details there.
- The site's name uses non-Latin letters and may imitate a well-known name. Check it before you open it.
- The link has a username before the site's name, a trick to hide where it leads. The real site is the one written above.
- The link leads to a numeric address, not to a site's name. Well-known sites do not do that.
What we measured on the picture
- The contrast is enough: :1 between the squares and the background; the limit we go by is 4:1. The contrast is weak: :1; the limit we go by is 4:1. Make the squares darker or the background lighter. The code is light on a dark background. Many phones do not read that: swap the two colours.
- The margin is enough: 4 empty squares or more around the code. The margin is narrow: empty squares around it, where the standard asks for 4. Most phones still read it, but put nothing right against it. There is not enough margin around the code in the picture. Leave a space in its background's colour around it, 4 squares wide.
- The picture is sharp enough: pixels for each square. The picture is small: only pixels for each square, so its edges come out ragged when enlarged. Print from an SVG or a PDF file, or download a larger PNG.
- Reading it scaled down, as a camera sees it from a distance… It still reads when scaled down to three pixels per square, which is close to what a camera captures from a distance. It was read at full size but not when scaled down: the shape of the squares, the logo or the colours weaken it. Simplify the design or print it larger.
This code has squares across, and its error correction level is .
Print it at least cm wide, its margin included.
What the check measures, and what it does not
The check reads the picture with ZXing, an open-source reader, and measures the contrast, the margin and the number of squares on it. The size is worked out with the same rule as the size calculator.
It measures the picture, not the paper: it does not know the paper or its gloss, the ink, or the curve of a package. So print one copy and scan it with more than one phone before the whole run.
Questions about the check
Which picture do I choose?
The file that goes to the printer once the designer has placed the code in it, exported as a picture. Most of what weakens a code happens in the artwork: shrinking it, changing its colours, or pushing it against the edge.
What is the error correction level?
How much damage or covering a code can take and still scan. There are four levels: L, M, Q and H, from lowest to highest; H withstands the most and is what a logo in the middle needs.
Does it check a code that was not made with Kuody?
Yes. It checks any QR code, whoever made it.