What size should a QR code be?
About a tenth as wide as the distance it's scanned from, if the code is a simple one. A denser code needs to be bigger, because it packs smaller squares into the same space. No matter what, they should never be smaller than about 1 square inch (approximately 2.5 cm) to ensure they will scan well.
Work out your size
Enter your best estimation of how far people will be when they scan. You will get the smallest size that each code should be printed at: once for a 1QRL short link, and once for the same destination pasted into a QR generator as a long URL.
Common placements
Minimum widths to ensure clean QR reads at the usual distance people will be scanning from. Size for the farthest reader, not the average one.
| Placement | Scan distance | 1QRL short link | Long URL, as-is |
|---|---|---|---|
| Business card | Scan distance10 in (25 cm) | 1QRL short link1 in (2.5 cm) | Long URL, as-is2¼ in (5.5 cm) |
| Menu | Scan distance20 in (50 cm) | 1QRL short link2 in (5 cm) | Long URL, as-is4¼ in (11 cm) |
| Product packaging | Scan distance3 ft (90 cm) | 1QRL short link3¾ in (9.5 cm) | Long URL, as-is7¾ in (19.5 cm) |
| Poster | Scan distance6 ft (1.8 m) | 1QRL short link7¼ in (18.5 cm) | Long URL, as-is15½ in (39.5 cm) |
| Sign | Scan distance10 ft (3 m) | 1QRL short link12 in (30.5 cm) | Long URL, as-is2 ft 2 in (66 cm) |
| Shop window | Scan distance30 ft (9 m) | 1QRL short link3 ft (91.5 cm) | Long URL, as-is6 ft 5 in (2 m) |
| Banner | Scan distance50 ft (15 m) | 1QRL short link5 ft (1.5 m) | Long URL, as-is10 ft 8 in (3.3 m) |
Where the numbers come from
The usual rule of thumb is ten to one. Scan distance divided by 10 gives a suggested width for the code. It is a good rule of thumb for a small, simple code, but it says nothing about what's actually going on inside.
A camera doesn't read all codes equally—it reads the individual modules (the little black and white squares) inside each one. In real-world usage, it matters much more that each module is big enough, rather than the entire code. So we take ten to one as true for a 25 × 25 code, which is the smallest grid that holds a typical short link, and scale up from there: a code with twice the modules across needs twice the width to keep each module the same size.
A typical campaign URL pasted in as it is makes a 53 × 53 code, so it has to be printed far bigger than a 1QRL code in order to scan well from the same spot. That gap is why 1QRL encodes the short link.
The floor is there because phone cameras often struggle to focus on anything smaller, no matter what is inside it.
Before you print
Leave a margin. The QR standard asks for blank space that is an extra 4 modules wide on every side, called the quiet zone. The sizes above don't account for it. Text, borders, or a busy background inside that margin will make a code harder to find.
Keep the contrast high. Dark squares on a light background scan best. Light on dark works with most phones, but not all of them.
Mind the surface. A code that wraps around a bottle or sits behind glass will scan worse. Go up a size in situations like these.
Adding a logo raises the module count. A logo hides part of the code, so 1QRL switches to stronger error correction to make up for it, which needs a slightly bigger grid. What error correction costs.
Test it at full size. Print one copy at the real size, stand where your farthest readers will stand, and scan it with a couple of different devices.