Why your QR code will not scan
A QR code usually fails to scan for one of five reasons: not enough contrast between the code and its background, no quiet-zone margin around the edge, the printed code being too small for the scanning distance, a centre logo covering too much of the pattern, or inverted colours with a light code on a dark background.
Fix the five common causes
- Contrast: keep the code dark on a light background, with a contrast ratio of at least 3.5:1. Pastel-on-pastel looks nice and scans badly.
- Quiet zone: leave a clear margin of at least four modules around the code. Cropping the margin is the single most common mistake.
- Size: as a rule of thumb the printed code should be about one tenth of the scanning distance, so a code read from 2 m needs to be roughly 20 cm across.
- Logo: keep the centre logo small and raise the error-correction level to H so the missing area can be reconstructed.
- Inversion: light code on a dark background fails on many older scanners; invert it back if in doubt.
Print-specific problems
Export SVG for print. A PNG scaled up for a poster becomes soft, and soft module edges are exactly what a camera struggles with. Avoid glossy laminate directly over the code, and never print a code over a photograph.
Test before you print
Scan the code with at least two phones, one iPhone and one Android, at the real distance it will be read from. Test it after it has been placed into the final design, not only in the generator.
Frequently asked questions
Do QR codes expire?
A static QR code encodes your content directly and never expires. Only dynamic codes that redirect through a third-party service can stop working if that service shuts down or the link is deleted.
Can I put a logo in the middle of a QR code?
Yes, if the error-correction level is set to H and the logo covers no more than about 20-25% of the code area.
Which colours are safe?
Any dark foreground on a light background with strong contrast. Gradients are fine as long as every part of the gradient stays much darker than the background.
PNG or SVG for printing?
SVG, because it stays sharp at any size. Use PNG at 1024px or larger only for screens and small prints.
Last updated 2026-09-15.