QR code size and error correction: how big to print and which level to choose
Short answer: print a QR code at least 2 × 2 cm for anything held in the hand, make its width about one tenth of the distance people will scan from, keep a blank margin four modules wide around it, and choose error correction M for clean codes or H if you add a logo or expect wear. The rest of this guide explains where those numbers come from and when to bend them.
How a QR code is built (the part that matters for size)
A QR code is a square grid of modules. The smallest version is 21 × 21 modules; the largest is 177 × 177. The generator picks the version automatically based on two things: how much data you put in, and the error correction level you choose. More data or more correction means more modules.
That matters because the printed size is fixed by your layout. If you have a 3 cm space on a label, a 25-module code gives each module more than a millimetre. A 57-module code squeezes each one to about half a millimetre. Smaller modules need a sharper print and a better camera. So size is really about module size, and module size depends on your content plus the error correction level.
Choosing a print size
The one-tenth rule is a good starting point: divide the expected scanning distance by ten. Then adjust upward for long links, poor lighting or awkward angles.
| Where it is used | Typical scan distance | Suggested minimum width |
|---|---|---|
| Business card, product label | 15–20 cm | 2 cm |
| Flyer, receipt, table tent | 25–40 cm | 3–4 cm |
| A4 poster on a notice board | 0.5–1 m | 5–10 cm |
| Shop window, roll-up banner | 1.5–2 m | 15–20 cm |
| Large banner across a room | 4–5 m | 40–50 cm |
These are minimums for a fairly short link. If your code looks dense, go one step larger. Think about angle too: a code mounted high on a wall is scanned at a slant, which shrinks it in the camera's view.
Check the module size, not just the overall size
A practical check is to estimate how many modules sit across the code and divide the printed width by that number. When individual modules drop below about half a millimetre, ordinary office printers start to bleed ink between them and older phones begin to struggle. If you are in that territory, either print larger or put less data in the code.
The quiet zone
The quiet zone is the empty margin around the code. The QR standard asks for four modules on each side. It tells the scanner where the code ends and the background begins. On a busy design, a white box around the code with that margin intact is the simplest way to keep it readable. Do not count the quiet zone as part of the code width in the table above; it comes on top.
Error correction levels explained
QR codes use Reed–Solomon error correction, the same family of technique used on CDs. Part of the grid stores redundant data so the scanner can rebuild what is missing or unreadable. You choose how much redundancy to include:
| Level | Approximate recovery | Good for |
|---|---|---|
| L (Low) | about 7% | Screens, very clean prints, maximum data in minimum space |
| M (Medium) | about 15% | Most flyers, documents and labels without a logo |
| Q (Quartile) | about 25% | Codes in kitchens, warehouses or outdoors that may get dirty |
| H (High) | about 30% | Codes with a centre logo, or surfaces that wear quickly |
The trade-off is simple. Higher levels make the code more robust against damage, but they add modules, so at the same printed size each module gets smaller. For a long link printed small, H can actually be less reliable than M because the grid becomes too fine. For a short link with a logo, H is the right choice.
How I choose in practice
- No logo, clean environment, short link: M.
- No logo, long link, small space: L or M, and shorten the link if you can.
- Logo in the middle: H, every time.
- Outdoor signs, packaging that gets handled, floor stickers: Q or H, and print larger.
The QR Code Generator on Online Toolsz starts at H by default, which is a safe choice when you are unsure. Switch to M if you have a long link and a small space, and compare how dense the preview looks before downloading.
Logos, colours and other design choices
A logo removes modules from the centre of the code, and error correction fills them back in. Keep it modest: a logo that covers a small part of the code leaves spare capacity for scratches and blur. Never place anything over the three large squares in the corners, which the scanner uses to find and orient the code. In our generator the logo has a fixed pixel size, so it takes a larger share of a small code; use a higher size setting when you add one.
For colours, the rule is contrast. A dark foreground on a light background, with the difference obvious even on a black-and-white photocopy, will scan. A quick test is to print the code in greyscale: if the modules and the background look similar in grey, a phone camera will struggle too.
Export settings that affect print quality
- Generate large, do not stretch. Move the size slider up before downloading so the PNG has more pixels to work with.
- Keep it as PNG. Re-saving as JPEG adds soft, blotchy edges around the modules.
- Lock the proportions. When placing the image in a word processor or design tool, scale from a corner with the aspect ratio locked.
- Do not crop the margin. The downloaded PNG already includes the quiet zone; leave it there.
Pre-print checklist
- Link tested in a private browser window.
- Code width at least one tenth of the scanning distance, and never under 2 cm.
- Four-module margin intact on all sides.
- Error correction H if there is a logo; M or Q otherwise.
- Strong contrast, checked in greyscale.
- One proof printed at real size and scanned with two different phones.
If something still fails, the QR code troubleshooting guide works through each cause by symptom. For a worked example in a demanding setting, see QR codes for restaurant menus.
FAQ
What is the smallest QR code that still scans?
For a short link scanned up close, about 2 × 2 cm is a safe practical minimum. Smaller can work with very short content and high-quality printing, but test carefully before committing to a print run.
Does higher error correction always mean better scanning?
No. It makes the code more tolerant of damage, but it adds modules. On a small print with a long link, a lower level may scan more easily because each module is bigger.
Can I make a QR code bigger after downloading it?
You can, but enlarging a small raster image can blur the edges. Generate it at a higher size setting instead, and scale it down in your layout if needed.
Does the quiet zone have to be white?
It has to be plain and light, matching the code's background colour. A cream or pale background is fine as long as nothing else sits inside the margin.
Which error correction level should I use for a business card?
M is usually enough for a short website link on a card. Use H if you place a logo in the middle.