How the calculator works
It applies a widely used rule of thumb: a QR code should be about one tenth as wide as the distance it is scanned from. A code read from 1 m away should be roughly 10 cm wide; from 3 m, roughly 30 cm. Two things push the number up. A code that holds more data (a long web address, Wi-Fi details or a contact card) is made of smaller squares, called modules, so it needs more width to stay readable. And rough surfaces such as uncoated board, fabric or a curved bottle blur the edges of modules, so they need more width too. The calculator multiplies the base figure for each, and never goes below 2 cm, the practical floor for a code held in the hand.
Quick reference by situation
- Business card, flyer, receipt (20–40 cm)
- 2–3 cm (0.8–1.2 in)
- Table tent, menu, counter card (30–60 cm)
- 3–6 cm (1.2–2.4 in)
- Shop window, yard sign (1–1.5 m)
- 10–15 cm (4–6 in)
- Poster on a wall (1–2 m)
- 10–20 cm (4–8 in)
- Banner or large sign (3 m)
- 30 cm (12 in) or more
- Code shown on a TV or projector (3 m)
- About 30 cm of code on the physical screen
Why a short link scans better at small sizes
The number of modules in a QR code grows with the amount of data inside. A dynamic QR code holds only a short link, so it has far fewer modules than a static code that contains a long web address, a Wi-Fi password or a whole contact card. At the same printed width, fewer modules means bigger modules, and bigger modules scan more reliably on small labels, rough paper and cheap printers. It is one reason to use a dynamic code for anything printed small. Dynamic codes also let you change the destination after printing.
Check these before you print
- Quiet zone. Keep a blank border of at least four modules on every side. Text, images or a box edge touching the code is the most common cause of failed scans.
- Contrast. Dark modules on a light background. Inverted codes (light on dark) fail on some scanners.
- Logo size. A logo in the middle removes modules. Use high error correction and keep the logo to about a fifth of the code or less.
- Proof. Print one on the real material and scan it with an iPhone and an Android phone from the real distance.
Frequently asked questions
What is the minimum size for a QR code?
About 2 cm (0.8 in) wide for a code held in the hand, printed sharply with a clear border. Anything scanned from further away needs more: divide the distance by 10.
How far away can a QR code be scanned?
Roughly ten times its width under normal conditions. A 10 cm code is comfortable at about 1 m, and a 30 cm code at about 3 m.
Does a bigger QR code scan better?
Up to a point. A larger code is easier to read from a distance, but it also has to fit the space and keep its blank border. Past the distance you need, extra size does not help.
Do I measure the code with or without the blank border?
Measure the dark pattern only. Then add the blank border of at least four modules around it on every side.