QR code guides

• Why your QR code isn't scanning

  A phone camera refusing to read a QR code almost always traces back to one of eight causes. Here's how to diagnose and fix each one, worst offenders first.

• What size should a QR code be?

  The minimum safe width for a printed QR code is the viewing distance divided by ten. Worked examples for business cards, table tents, posters, and billboards.

• Can a QR code be light on dark?

  Light-on-dark QR codes can scan reliably, but contrast and scanner assumptions matter more than colour. Here's what to check before you print one.

• Static vs dynamic QR codes

  Static QR codes are permanent and free forever; dynamic ones are editable and trackable but depend on a service staying online. Here's when each is right.

• How big can a logo on a QR code be?

  Measured logo size ceilings by error correction level: L 17%, M 25%, Q 29%, H 30% of the code's width, not area. Why padding shrinks these further.

• QR code error correction levels explained

  L, M, Q, and H trade robustness for density. Higher levels recover from more damage but pack more modules into the same code. Here's how to pick one.