We're the Perfect Print team. You generate a QR code, print it on a flyer or a label, hold up a phone — and nothing happens. The usual cause isn't a bad code; it's that the code printed too small, or with no margin around it. A QR code needs a minimum physical size to be read, and that size depends on how far away the scanner sits. Get the dimensions right and printing it correctly is the easy part.
Size scales with scan distance
The rule of thumb scanners and signage designers use is simple: a QR code should be about one-tenth of the scanning distance. If a phone reads it from arm's length, around 10 inches (25cm), the code should be roughly 1 inch (about 2.5cm) on a side. A poster meant to be scanned from a few feet away needs to be several inches across. So before you set a size, picture how far the reader will stand — a card in the hand and a sign on a wall are very different jobs.
As a floor, we'd treat about 0.8 inch (2cm) on a side as the smallest you should go for close, hand-held scanning. Below that, ordinary printers and cameras struggle to resolve the fine modules, especially if the code carries a lot of data. When in doubt, go a little bigger — the cost of an oversized QR code is nothing; the cost of one that won't scan is a reprint.
Leave the quiet zone clear
A QR code needs empty space around it to be recognized — the quiet zone. The spec calls for a clear margin of at least four modules (the small squares) on every side, which in practice means leaving a blank border roughly the width of a few modules all around. Crowd the code with text or a border touching its edge and many scanners give up. When you place the code, reserve that white margin deliberately rather than trimming right to the pattern.
Place it at an exact size and print at 100%
This is where sizing has to be precise, and where a photo editor lets you down: a crop changes pixels on screen, not the printed inches, and fit to page rescales the whole layout, shrinking your carefully chosen code. In Perfect Print you set the QR image to an exact size — say 1 inch (about 25mm) square — so it's placed at actual size, with the quiet-zone margin kept around it. Print at actual size (100%), then measure the printed code with a ruler and test-scan it from the real distance before you make a batch. Use solid black on a plain white background and keep the contrast high so the camera reads it cleanly.
Perfect Print
A free app that places a QR code at an exact size and prints at 100%, so it scans reliably with the quiet zone intact. Millimeter-precise. No sign-up, iPhone / Android.
Learn more about Perfect PrintFrequently asked questions
What is the minimum QR code size?
For close, hand-held scanning, treat about 0.8 inch (2cm) on a side as the floor. As a general rule, make the code about one-tenth of the scanning distance, so larger signs need larger codes.
Why won't my printed QR code scan?
Usually it printed too small or too low-contrast, or it has no quiet zone. Set an exact size, keep a clear white margin around it, use solid black on white, and print at actual size (100%).
What is the quiet zone?
It's the blank margin around the code — at least four modules wide on every side. Without it, many scanners can't lock onto the pattern, so reserve that white space rather than trimming to the edge.
How do I make sure the size holds when printing?
Place the code at an exact size in Perfect Print and print at actual size (100%), never fit to page. Then measure with a ruler and test-scan from the real distance before printing a batch.