What Size Should a QR Code Be? A Print Sizing Guide

A QR code that is too small does not degrade gracefully. It does not scan slowly or work at close range — it simply fails, and the person gives up after about three seconds. Because the failure is silent, most people never learn it happened.

Sizing a code correctly takes one piece of arithmetic and one thing almost everyone forgets. Both are below.

The 10:1 rule

The industry rule of thumb is that a QR code should be at least one tenth as wide as the distance it will be scanned from. Divide the viewing distance by ten and you have your minimum width.

So a code on a poster people read from two metres away needs to be at least 20cm wide. A code on a menu held at 30cm needs about 3cm. The rule is approximate and errs on the safe side, which is what you want — the cost of a code being slightly too big is aesthetic, and the cost of it being slightly too small is that your campaign does nothing.

Minimum sizes by scanning distance

Applying the rule, with a floor of about 2cm because below that even a close scan becomes unreliable:

These are minimums, not targets. If you have the space, going 25–50% larger costs nothing and buys tolerance for bad lighting, older phone cameras, and people who do not hold still.

The quiet zone almost everyone forgets

A QR code needs a margin of blank space around all four sides for a scanner to find its edges. The specification calls this the quiet zone, and it must be at least four modules wide — a module being one of the small squares that make up the pattern.

In practice that means roughly a 10% margin around the code, and it must be genuinely blank. This is the single most common design mistake in printed QR codes: a designer crops tight to the pattern to save space, or runs text or a background image right up to the edge, and the code stops working.

• Do not crop to the pattern. Keep the white margin the generator gives you.
• Do not place text, logos or borders inside the margin. A decorative frame touching the code is enough to break it.
• Do not put the code on a busy photograph. Even with a margin, a patterned background confuses edge detection. Put it on a plain panel.

Longer data means a bigger code

This is the part that catches people out. A QR code's pattern is not a fixed grid — it grows as you add data. The smallest version is 21×21 modules; the largest is 177×177. More characters means more modules, and more modules packed into the same printed width means each module is physically smaller.

So two codes printed at the same 3cm can behave completely differently. One holding a 20-character link scans instantly. One holding a 120-character tracked URL with UTM parameters has modules less than half the size, and struggles.

The practical fix is to shorten what you encode:

• Use a short URL rather than a long path with query parameters.
• Drop UTM parameters from the encoded link and apply them at the redirect instead.
• For contact codes, remove vCard fields nobody will look up — every field adds modules. The vCard generator shows the pattern getting denser as you add them.
• Use a dynamic code, which only ever encodes a short redirect link regardless of how long the real destination is. This is the most reliable way to keep a small code simple.

As a rough guide, a module should end up no smaller than about 0.4mm on the printed piece. If you know your module count, divide your intended width by it and check.

Error correction: useful, but not free

QR codes carry redundant data so they still scan when partly damaged or obscured. There are four levels:

Higher correction means more redundant data, which means more modules, which means smaller modules at the same printed size. Turning error correction up to compensate for a small code is self-defeating — you make the pattern denser in exchange for damage tolerance you did not need.

Use M for most printing. Go to Q or H only when you have a specific reason: a logo covering the centre of the code, printing on fabric or a curved surface, or a label likely to get scuffed. And when you raise the level, raise the printed size to match.

Getting the file right

Sizing is only half the job. The file you hand the printer matters just as much.

• Send vector, not raster. An SVG or EPS scales to any size with perfectly sharp edges. A PNG enlarged to poster size gives soft, blurred module edges that scanners read badly. Every code from our free generator downloads as SVG.
• If you must use PNG, export at 300 DPI at final print size — not at screen size and scaled up.
• Keep it dark-on-light. Scanners expect a dark pattern on a light background. Inverted codes work on some readers and fail on others; it is not worth the risk.
• Keep contrast high. Black on white is ideal. Mid-grey on beige is a common designer choice that measurably reduces scan rates.
• Do not stretch it. A QR code must stay square. Non-uniform scaling breaks it.

Sizes for common formats

A starting point for the formats people ask about most. Round up if you have room.

Test it properly before you print

Checking the code on your screen proves nothing — screens are backlit and sharp in a way paper is not. Do this instead:

1. Print it at final size on the actual stock, or as close as you can get.
2. Stand where the reader will stand and scan from there, not from 20cm away.
3. Try more than one phone, including an older one. Camera quality varies more than people expect.
4. Test in the real lighting — a dim restaurant, a bright street, a glossy laminate reflecting overhead lights.
5. Scan the actual proof from the printer, not just your office printout. Ink spread on the final stock can thicken modules enough to matter.

If it fails any of these, the fixes are usually size, quiet zone, contrast, or data length — in that order of likelihood. Why QR codes fail to scan goes through the full list of causes.