Fix it
QR code tags and stickers not scanning? Six fixes for labels
The short answer
QR code tags and stickers usually stop scanning for one of three reasons: the code is too small for what is inside it, the surface is shiny or curved, or the label printer has blurred the squares. Fix the size first, then the material, then the printer.
Labels fail in ways a poster never does. These are the six fixes to try, in the order that solves most cases.
1. Shorten what is inside the code
Tags are small, so every extra square makes each one tinier. A long product address with tracking tags can double the number of squares. Point the code at a short link instead. A dynamic QR code always holds a short link, so it stays simple however long the real page address is.
2. Print it at least 2 cm wide
Most phones need about 2 cm (0.8 inches), border included, for a short link. Swing tags, jar lids and cable labels are often printed at 1 cm to fit, and that is the most common reason they fail.
3. Keep the white border
Stickers are often cut right to the edge of the code to save space. The camera needs a clear margin, about four squares wide, to find the code. If the sticker has to be small, make the code smaller and keep the border, not the other way round.
4. Matte, flat, and away from the seam
Glossy laminate reflects light straight back at the camera and wipes out part of the code. Use matte stock or a matte finish. On bottles and tubes, a code that wraps around the curve bends out of shape. Turn it so its height runs along the curve, or keep it narrow, and keep it clear of seams and folds.
5. Check the label printer
Thermal and cheap inkjet label printers can bleed ink, so black squares swell into the white ones. Print at the printer's highest quality, send a vector file such as SVG or PDF, and check a printed tag up close. If the squares touch where they should not, go bigger.
6. Dark on light, never the reverse
A white code on a black or kraft brown tag looks good and fails on a lot of phones. Keep the squares darker than the background, with strong contrast. Coloured codes are fine when the colour is deep and the background is pale.
Test a real tag before the full run
Print one tag on the actual material and stick it on the actual product. Scan it with two different phones in normal light. If the tags are already printed and the code was dynamic, you can at least change where it points, so a bad link is never the problem.
Questions
Why do my QR code stickers scan on some phones but not others?
The code is close to the limit, usually too small or low in contrast. Newer phones cope, older ones do not. Print it bigger or with stronger contrast.
Will a QR code sticker scan on a round jar?
Yes, if the code stays small compared to the curve. Keep it on the flattest part and away from the seam. A matte label helps a lot.
What size should a QR code tag be?
At least 2 cm (0.8 inches) wide, border included, with a short link inside. Go to 3 cm if the content is long or the printer is basic.
Can I fix QR code tags that are already printed?
Not the print itself. If the link is the problem and the code is dynamic, change where it points. If the print is the problem, a larger sticker over the top is cheapest.