A QR code that scans perfectly on a screen can fail completely once it is printed and placed on a table. The usual reason is not the ink or the paper; it is size. A code that is too small for the distance it must cover gives the camera too little information to resolve, and no amount of good design rescues it. The good news is that size is easy to reason about, because the rule that governs it is simple and physical.
Size Is a Distance Question, Not a Style Question
Print size and scan distance are two ends of the same measurement. A camera needs enough of the pattern present in the image to decode it. The further away the camera is, the smaller the pattern appears, and the more the individual squares blur together. A code that is comfortable at arm's length across a table may be impossible from across a room.
This is why the question "how big should the code be?" has no single answer. The correct answer always begins with another question: from how far away does someone need to read it? Set the distance first, and the size follows.
A Simple Rule of Thumb
The working rule used across print work is a ratio: the printed height of the code should be roughly one tenth of the distance from which it will be scanned. That relationship is a rule of thumb, not a guarantee, but it is a reliable starting point and it scales cleanly.
- If someone will scan from close range, a smaller code is workable.
- If someone must scan from a full step away, the code grows accordingly.
- If someone must scan from across a room, the code grows a great deal, because the distance has grown a great deal.
Treat the ratio as a floor rather than a target. A code slightly larger than the rule requires is more forgiving of a tired camera, a smudge, or a glance that arrives at an angle.
Two practical notes sit alongside the ratio. The first is that added detail, such as a logo or a denser error correction level, packs more into the same square area and makes the pattern finer, so a busy code needs more size than a plain one to read from the same distance. The second is angle: a code viewed from the side is effectively further away in the direction the camera sees, so a code that will be read at an angle should be sized as if the distance were greater than it looks.
Reading Across a Table
Most review and menu cards are read from table distance: a person seated, phone in hand, looking at a small stand a short reach away. This is the easiest case, and the range in which almost any sensibly sized code performs. The risk is not distance but crowding, because a code competing for space with a logo, a line of text and a border can be shrunk until it no longer carries enough readable detail.
Keep the printed pattern itself large enough to survive that crowding. Decorative elements can be trimmed; the code cannot.
Matching Size to Material and Place
The material matters too. A code on a PVC or acrylic card can be printed large and placed at a comfortable height, while a sticker applied to an uneven or distant surface has to be sized for the angle and the reach it will actually meet. A code on the back of a counter, read from the customer's side, needs more size than a code handed directly to a person.
Consider where the eye will be, not where the printer is. The product guide is a useful place to think this through before choosing a format.
Testing Before the Print Run
Print size is one of the few decisions you can test cheaply. Print a draft at the intended size, place it where it will live, and scan it from the real distance with a real phone. Do this before committing to a full run at a 100 pcs minimum, not after. If the code reads comfortably from the honest distance, the size is right. If you have to lean in, the code is too small, and it is far cheaper to find that out on a draft than on a finished table card.
If you tell us the distance the code must cover and where it will sit, we can advise on size as part of the print setup. Questions are welcome on WhatsApp at +86 151 0247 7198 or by email at nina@cwtape.com.