How to use it
- Enter the distance people will scan from. A menu on a table is about 50 cm. A poster at eye level is 1 to 2 m. A shop window from the pavement is 3 m.
- Pick the version your code will be. If you do not know, paste your content into the capacity calculator and it will tell you.
- Read off the minimum size. Print larger if you can; nothing is lost by being generous.
In practice
A short link is the cheapest way to make a code print smaller. https://getqrstudio.app/scan is version 2. The same page reached through a long tracking URL with five parameters can be version 6 or 7, with modules half the size.
Common mistake
Sizing the code for the distance you test it from at your desk, then mounting it above a doorway. Measure the real distance, or design for the furthest plausible reader.
▸The maths
Minimum size = scan distance ÷ 10. Module size = minimum size ÷ (modules per side + 8), the 8 being the quiet zone on both sides. Pixels needed = size in inches × DPI. A 300 DPI print of a 5 cm code needs about 591 px; 150 DPI is acceptable for large-format posters viewed from afar.
Try it yourself
Not sure your printer agrees with the maths? Print the test sheet, which has the same code at eight sizes, and scan each one from the real distance.