QR code size for printing: the one-tenth rule, long links and a test sheet

A small QR code looks tidy in a layout, but on paper the phone camera may not read it. Start from the scanning distance, then adjust for the link, the paper and the printer. For a code that people scan up close with a phone in hand, the minimum is 2×2 cm (about 0.8 in on a side).

Harbor Books, a bookstore with a small cafe, puts 2 cm stickers on its shelves and 5 cm (about 2 in) table tents on the cafe tables. Its window poster is read from 2 m (about 6.6 ft). Round the size up whenever you hesitate, because a saved centimeter does not pay off if the run has to be printed again.

Count from the scanning distance

Make the code size one tenth of the distance people scan it from. A menu held at the table is read from 25–30 cm (about 10–12 in), so its code needs 2.5–3 cm (about 1–1.2 in). People read the Harbor Books window poster from 2 m, so its code starts at 20 cm (about 8 in).

The "Size of one QR code (cm):" slider in "Step 2 · Look and size" goes from 1 to 15 cm in steps of 0.1 cm. By the same rule, a 15 cm (about 5.9 in) code can be scanned from 1.5 m (about 4.9 ft). For a code over 15 cm, download an SVG file that scales without loss and have a print shop make it at the size you need. The other way is "Sign: one code per sheet" in "Layout:", where every line of the list becomes its own sheet with a large code, a title and a caption.

A starting size for each scenario

Under the slider, four preset buttons set 2, 3, 5 or 8 cm, and each names the things it suits. The distance in the table follows from the one-tenth rule.

The largest preset, 8 cm (about 3.1 in), is for signs on a wall or a stand. Each preset button also shows how many codes fit on your sheet, for example "≈40 per sheet", or says "does not fit". Click "other" to enter your own size.

The size you pick also sets the count per sheet, A4 or US Letter. Without captions, you get 40 codes on A4 at 2 cm and 15 at 4 cm. On Letter you get 35 codes at 2 cm and 12 at 4 cm. For other sizes, see the article on codes per sheet on A4 and Letter. When you put many codes of one size on a sheet, the preview shows the count for your own list.

A long link needs a bigger code

A QR code is a square grid of small squares called modules. The longer the content, the more modules on each side, and at the same code size each module gets smaller. The menu link of Harbor Books, https://example.com/menu, has 24 characters. With UTM tags for the site analytics it grows to 75: https://example.com/menu?utm_source=qr&utm_medium=print&utm_campaign=tables. Here are the Harbor Books codes side by side at the 2 cm minimum.

On an office printer at 300 dpi, keep the module at 0.4 mm or more, and on a thermal label printer keep it at 0.5 mm or more. A 600 dpi laser can print smaller modules, but on plain paper a module below 0.4 mm is hit or miss. The 300-character link falls below 0.4 mm at 2 cm. It needs at least 2.5 cm on an office printer and 3.1 cm on a thermal one.

The size to print is the largest of three numbers: the 2 cm minimum, one tenth of the scanning distance and the smallest size the module threshold allows. By module size alone the menu link could go down to 1 cm, so the 2 cm minimum decides. Check your own content in the calculator. If the codes will have a logo, turn on "Logo in the center (correction H)" there, because a logo adds modules.

For a long link, the best fix is a short address on your own domain that redirects to it. Paste both links into the list, and the preview shows the two codes next to each other. Point the loupe at the preview to see what each code contains.

The QR code standard also asks for a quiet zone of 4 modules on each side, 3.2 mm for the menu link at 2 cm. On a sheet every code has a 0.3 cm frame margin on each side, and the gap between codes, 0.6 cm by default, adds more, so you do not need to add space yourself.

Paper and printer change the math

An inkjet printer with a low cartridge prints black as gray, and a gray code on white is harder to read than a black one. Glossy paper and lamination reflect the lamps, and part of the grid disappears in the glare. On textured paper small modules blur along the fibers. On a large code each of these is tolerable, but on a small one they add up.

In harsh conditions, such as outdoors, in a warehouse or in a kitchen, make the code 0.5 cm larger than the one-tenth rule gives. A 3 cm code instead of 2.5 cm has 44% more area, each module is 20% larger, and the camera reads it more reliably.

Test the size on paper

Print the code at the chosen size on the paper you will use for the run. Scan it from the scanning distance with two phones, one of them a budget model. The size is right when a phone reads the code in 1–2 seconds and you do not have to tilt it. If it takes longer, add 0.5 cm and test again.

If you cannot decide between sizes, print the same code at 2, 2.5 and 3 cm. The form uses one size per run, so make three runs of one line each. Each PDF is a single sheet. Keep the size that both phones read right away, and if two sizes pass, keep the larger one. Test under the lighting where the code will go, because a camera that reads it under warehouse lamps can miss it in a dim cafe.

Print each test sheet at 100% ("Actual size") with "Fit to page" turned off, and measure the code with a ruler. A 2 cm code that measures 1.9 cm means the print dialog is still scaling. For a whole run, the same check is part of printing 100 QR codes with a pilot sheet. More on paper and print settings is in the QRsetter knowledge base.

FAQ

Next step

Tape the printed code where it will go, and step back to the scanning distance with your oldest phone. The size is right if the phone reads the code and opens the link from there, and you did not have to step closer.

Pick a QR code size from 1 to 15 cm and watch the preview redraw the sheet as you drag the slider.