Print it big enough for the distance people will stand at, keep the clear margin around it, use a dark pattern on a light background, and test the real printed thing before you order a thousand of them.
Size
The working rule is that a code needs to be about a tenth of the distance it will be scanned from. Someone holding a flyer is 30cm away and needs roughly 3cm of code. Someone reading a poster across a room is 3m away and needs 30cm.
- Business card, flyer, menu2–3cm across, minimum
- Window or A4 poster5–10cm
- Across a room25cm and upwards
- The margin around itRoughly four modules of clear space — in practice, do not crowd it
Where it goes
- Somewhere a phone can reach A code above head height or behind a counter cannot be scanned however well it is printed.
- Off the fold and off the curve A code across the fold of a leaflet or around a bottle is distorted before anyone tries.
- Away from glare Gloss laminate under a spotlight defeats a camera. Matt if you have the choice.
- With a line of text People scan a code when they know what they will get.
Test the printed article, not the filePrint one at final size on the actual material, and scan it with an ordinary phone, at the distance and in the light people will really be in. Printing shrinks and softens edges in ways a screen never shows.
Use a dynamic code for anything you cannot reprintIt is the difference between fixing a mistake in thirty seconds and paying for the print run twice. See dynamic versus static.
Related: customising the design.