QR code size, margin and quiet zone in QR by Zaweba

Two numbers decide whether a printed QR code is pleasant or painful to scan, and neither is about what it holds. In QR by Zaweba you set the size of the finished code in millimetres, margin included, and the margin itself in modules. Get these right and nearly any phone reads the code first time.

Both live alongside the colours and error correction, and the live preview checks them on every change.

Modules and the quiet zone

A QR code is a grid of small squares called modules. How many modules there are depends on how much the code holds and on the error correction level: a short link makes a coarse grid, a long contact card a fine one.

Around the grid sits the quiet zone, an empty border that tells a scanner where the code starts and stops. Without it, a scanner can mistake nearby text, a picture or the edge of a table for part of the code. That's why QR by Zaweba measures the margin in modules: the border needs to be in proportion to the squares, not a fixed number of millimetres.

If the margin is too small to read back, the preview warns you. The warning is there because a cramped code may scan on your desk and fail on a cluttered poster.

Size in millimetres

The size you set is the size of the whole finished code, margin included. Saved as SVG or PDF, it prints at exactly that size. A PNG is made with each module a whole number of pixels, so the squares stay crisp, and its dpi is written into the file; because of that rounding, a PNG's printed size can differ slightly from the size you asked for.

Choosing a size is a matter of distance and density. A code read at arm's length on a business card can be small. A code read across a room, on a poster or a shop window, needs to be much bigger. A dense code, with a lot of data or a high error correction level, needs more size than a simple one at the same distance, because its modules are smaller.

Rather than rely on a rule, print a test at the size you have in mind and scan it from where people will actually stand.

How it fits with the other settings

Every other setting affects the grid. A longer link, more contact details or a higher error correction level adds modules, which shrinks each module at the same size. Adding a logo raises error correction to High, which does the same. So when you add content or a logo, look again at the size.

Colours matter to the margin too. The quiet zone is only quiet if it is clearly the background colour. On a transparent background, the margin is whatever sits behind the code once it is placed, so leave clear space round it in your layout.

Your size, margin, error correction and colours are remembered between uses, so once you have settings that suit your printer or your sign maker, they are there next time.

Mistakes to avoid

The commonest mistake is trimming the margin to make the code fit a tight space. Make the code smaller instead and keep the border; a smaller code with a proper quiet zone usually scans better than a bigger one without.

The second is placing a code right against text or a busy picture, which eats into the quiet zone after the fact. The third is stretching a PNG in another program, which blurs the crisp modules. If you need a different size, change it in QR by Zaweba and save again, or use SVG or PDF, which scale cleanly.

The live check reads the app's own output. A quick scan of a printed test with your own phone, from a realistic distance, is the final word.