What size should a QR code be?
Make it at least 2 cm (0.8 in) wide for things read up close, and about one tenth of the scanning distance for anything read from further away.
The distance rule
A phone camera needs each square of the code to be large enough to see. A good working rule is a code width of one tenth of the distance: a code scanned from 1 metre should be about 10 cm wide, from 3 metres about 30 cm. Use the size calculator to work it out for your own distance and content.
The rule assumes a simple code. A long link or a lot of text makes more, smaller squares, so the code has to be bigger. A dynamic code keeps the pattern simple because it only holds a short link.
Typical sizes
Business cards and labels: 2 to 2.5 cm. Flyers and table cards: 3 to 4 cm. Menus and brochures: 3 to 5 cm. Posters read from a few steps away: 10 to 20 cm. Shop windows and banners read from across a street: 30 cm and up.
AI art and photo codes should be printed larger than plain ones, at least 3 cm, because the picture lowers the contrast.
Margin, contrast and file type
Leave a clear margin around the code, ideally four squares wide and never less than two. Keep dark squares on a light background with strong contrast. Send the printer a vector file, SVG, PDF or EPS, so the edges stay sharp at any size.
Before the full run, print one copy at the real size and scan it from the real distance with two different phones.