A Guide to QR Code Size, Margin and Resolution for Print

A QR code that scans fine on screen often fails on paper. The cause is nearly always size, margin, resolution or material. This guide lists what to check before you print. There is no exact minimum size that works for every code, and the figures below are rules of thumb, so confirm them with a test print.

How scanning distance relates to size

For a camera to read a code, each module has to appear at a certain minimum size in the frame. The farther away the scan, the larger the code must be. A common rule of thumb is about one tenth of the scanning distance.

• Close range such as business cards or invitations (about 20 to 30 cm): 2.5 to 3 cm or more
• Table stands and menus (about 30 to 50 cm): 3 to 4 cm or more
• Notice at a checkout counter (about 1 m): around 10 cm
• Posters and banners (several meters): distance divided by 10 at least, larger if you can

These values assume a plain, flat code with good contrast. If the address is long and the modules are dense, or if you use shapes, logos or image decoration, make it bigger. A higher error-correction level also makes the modules smaller at the same size.

The quiet zone is four modules

The empty area around a QR code is called the quiet zone. The standard (ISO/IEC 18004) is generally cited as requiring at least four modules on every side. One module is the width of a single dot.

1. Divide the width of the code body by its number of modules to get one module. For example, a 3 cm body with about 30 modules gives roughly 1 mm per module.
2. Keep at least four times that, about 4 mm here, empty on all sides.
3. Make sure borders, photos, fold lines and crop marks from the layout do not enter that area.

Vector and high-resolution files

A QR code is a grid of small squares, so blurry edges directly reduce recognition.

• Prefer a vector file such as SVG, which stays sharp at any size. Designed codes from Mandu QR can be saved as SVG.
• For PNG, calculate the pixels: pixels = millimeters / 25.4 x dpi. At 300 dpi, a 30 mm code needs about 355 pixels. More is better.
• Do not let a print shop enlarge a small PNG, because the edges blur. Never stretch it to change the aspect ratio either.
• Avoid screenshots or images that have been compressed repeatedly through messengers.

Material, coating and glare

• Glossy lamination, glass and acrylic reflect lights and can wash out part of the code. Matte coating or matte paper is safer.
• On curved surfaces such as cups and bottles the code bends. Make it larger and place it on the flattest area.
• Rough paper that absorbs ink, or thin paper that shows through, can smear the modules.
• Light dots on a dark background, or pale colors, lose more contrast after printing. Use strong colors.
• If it is a sticker, apply it flat with no wrinkles.

Pre-print checklist

1. Print one test copy at the exact final size.
2. Scan it with iPhone and Android, at the real distance and angle.
3. Check for glare under the lighting where it will be installed.
4. Confirm the four-module margin is intact.
5. Open the destination to be sure the address is correct.

A sample sizing sequence

1. Decide the scanning distance. If people scan from 40 cm at a table, start from around 4 cm.
2. The longer the address, the denser the modules, so add some margin to that size. Shorten the address if you can.
3. Test-print the code and scan it with several phones from the intended distance.
4. If it reads quickly, keep it. If it is slow, go one step larger and test again.

Mandu QR is free, needs no sign-up and saves PNG and SVG. Shaped codes, image codes, frames and captions are available on the same screen.

Open Mandu QR

"QR Code" is a registered trademark of DENSO WAVE INCORPORATED.