Scan & Generate
Free QR Code Print Size Calculator
The usual advice — make it a tenth of the scan distance — ignores how much data you put in. This calculator works out the module size your content actually forces, and tells you when the data, not the distance, is what sets the minimum.
Nothing you type leaves your device. The calculator is plain JavaScript running in your own browser. Your content is measured for its length and encoding mode and never uploaded — useful when you are sizing codes for links that are not public yet.
Paste the exact URL or text you will encode. Length is what drives the module grid, so a tracking parameter you forgot about really does change the answer.
Or start from a typical placement
Already Have a Size in Mind?
If the layout is fixed and the QR code has to fit a particular box, work the other way. Enter the width you have available and this tells you the module size it produces for the content above, and how far away it can realistically be read.
How the Calculation Works
Most QR code size advice stops at one rule of thumb: make the code about a tenth of the distance it will be scanned from. That rule is fine as far as it goes, but it treats every QR code as if it were the same. It is not — a code holding a 30-character link and a code holding a 200-character link are completely different objects at the same printed width.
Step 1 — content decides the module grid
A QR code is a grid of squares called modules. How many it needs depends on how much data you put in and how much error correction you ask for. That combination picks a version, from 1 to 40, and the version fixes the grid: modules per edge = version × 4 + 17. Version 1 is 21 across, version 10 is 57, version 40 is 177. Each step up divides the same printed square into more, smaller pieces.
Step 2 — the distance rule gives a first width
The 10:1 rule of thumb says the symbol should be about one tenth of the furthest distance it will be read from. Read at 30 cm, print about 30 mm. Read from 2 m, print about 200 mm. This is a widely used working figure rather than a requirement from the standard.
Step 3 — the module size decides whether it scans
Now divide that width by the module count and you get the X-dimension: the width of one module. This is the number that actually matters, because a camera has to resolve individual modules, not the code as a whole. For QR codes read at retail point of sale the GS1 General Specifications set an X-dimension range of 0.396 mm to 0.99 mm, with 0.495 mm as the target. Marketing and signage codes are not bound by those figures, but they are the only published limits with a standards body behind them, so this calculator measures against them and says so.
Step 4 — take whichever width is larger
Here is the part the 10:1 rule leaves out. If your content forces a dense grid, the width the distance rule suggests may produce modules below the minimum. So the calculator computes a second width — the module count multiplied by the minimum X-dimension — and recommends whichever of the two is larger. When the second one wins, the calculator says so explicitly: your data, not your scanning distance, is what is setting the size, and shortening the URL will do more than moving the poster.
Step 5 — add the quiet zone
ISO/IEC 18004 requires a clear margin of 4 modules on all four sides. That margin is not part of the symbol width but it is part of the space the code occupies, so a 41-module symbol actually needs 49 modules of room. On small codes this is a large share of the footprint, and crowding it is one of the most common reasons a technically correct QR code will not scan.
A Worked Example
Take a 100-character URL at error correction M, going on a table tent that people will scan from about 50 cm away.
- 100 bytes at level M needs version 6, so the grid is 41 × 41 modules.
- The 10:1 rule on 50 cm gives a symbol 50 mm wide.
- The data floor is 41 × 0.396 mm = 16.2 mm, which is smaller, so the distance rule wins and 50 mm stands.
- Module size is 50 ÷ 41 = 1.22 mm — comfortably inside the GS1 range.
- Adding the quiet zone, the code needs 49 × 1.22 mm = 59.8 mm of clear space on the card.
Move that same code to a business card scanned at 20 cm and the rule gives 20 mm, module size drops to 0.49 mm, and you are near the edge of what a phone camera will resolve. That is the case the simple rule cannot see.
Common Placements at a Glance
Sizes for a 100-character URL at error correction M (version 6, 41 × 41 modules). Shorter content allows smaller codes; level H or a longer link pushes every figure up.
| Placement | Scan distance | Symbol width | Module size |
|---|---|---|---|
| Business card, held in the hand | 20 cm | 20.0 mm | 0.49 mm |
| Product label on a shelf | 30 cm | 30.0 mm | 0.73 mm |
| Table tent or restaurant menu | 50 cm | 50.0 mm | 1.22 mm |
| A4 flyer or leaflet | 60 cm | 60.0 mm | 1.46 mm |
| Shop window, read from the pavement | 100 cm | 100.0 mm | 2.44 mm |
| Wall poster in a corridor | 200 cm | 200.0 mm | 4.88 mm |
| Trade show banner | 500 cm | 500.0 mm | 12.20 mm |
| Billboard | 2000 cm | 2,000.0 mm | 48.78 mm |
What the Geometry Does Not Cover
Every figure here assumes good printing and a cooperative surface. Several things shrink the real working distance without changing any of the arithmetic:
- Low contrast. Dark-on-light is what decoders expect. Inverted or low-contrast codes lose distance, and some scanners will not read them at all.
- Glossy stock and lamination. Reflections under shop lighting can wipe out whole regions of the grid.
- Curved surfaces. Bottles and cups distort the grid; codes on them need to be larger than the flat calculation suggests.
- Ink spread. Absorbent stock thickens dark modules. Printers compensate with bar width reduction; if yours does not, size up.
- A logo in the middle. That is error correction being spent, not free space. It is why level H exists, and level H needs a higher version for the same content.
The practical answer to all of these is the same: print one at the recommended size and scan it from the furthest point a real person would stand, on an ordinary phone rather than a dedicated scanner.
Related Tools and Guides
Frequently Asked Questions
What size should a QR code be?
The common rule is one tenth of the distance it will be scanned from: a code read at 30 cm should be about 30 mm wide, one read from 2 m should be about 200 mm. That rule is a starting point, not an answer, because it takes no account of how much data the code carries. A long URL forces a denser module grid, and at the size the rule suggests those modules can end up too small for a camera to resolve.
What is the X-dimension of a QR code?
The X-dimension is the width of a single module, the smallest square in the grid. It is the number that actually decides whether a code scans, because a camera has to resolve individual modules rather than the code as a whole. Divide the printed width of the symbol by the number of modules along one edge and you have it.
What is the minimum module size for a QR code?
For QR codes read at retail point of sale, the GS1 General Specifications set an X-dimension range of 0.396 mm to 0.990 mm, with 0.495 mm as the target. Codes on posters and marketing material are not bound by those figures, but they are the only published limits with a standards body behind them. Below about 0.25 mm a module is smaller than a typical phone camera can resolve at a comfortable distance, whatever the application.
Why does a longer URL need a bigger QR code?
More data means a higher QR version, and each version step adds four modules to each edge — version 1 is 21 modules across, version 10 is 57, version 40 is 177. Print two codes at the same physical width and the denser one has proportionally smaller modules. That is why shortening a URL is often the cheapest way to make a QR code scan reliably at a small size.
Does the quiet zone count towards the size?
It counts towards the space the code occupies, though not towards the symbol width itself. ISO/IEC 18004 requires a clear margin of four modules on all four sides, so a 29-module symbol actually needs 37 modules of room. On a small code that margin is a substantial share of the footprint, and encroaching on it is one of the most common reasons a technically correct QR code fails to scan.
What resolution should I export a QR code at for print?
Aim for a whole number of pixels per module rather than a particular DPI figure. If the export lands on a fractional number of pixels per module the renderer has to round some modules up and others down, which softens the edges the decoder relies on. The calculator shows the pixels per module for your chosen resolution so you can round the export up to a clean multiple.
Does error correction level change the size?
Indirectly, and often by more than people expect. A higher error correction level spends part of the symbol on recovery data, so the same content needs a higher version and therefore more modules. Level H, the one usually chosen for codes with a logo in the middle, can push content into a noticeably denser grid than level M — which then has to be printed larger to keep the modules readable.
Is anything I type sent to a server?
No. The calculator is plain JavaScript running in your own browser. The content you paste is measured for its length and encoding mode and never leaves your device, which matters if you are sizing codes for URLs that are not public yet.
Test the Size Before You Print 5,000 of Them
A calculator can only tell you what the geometry says. Print one at the size it recommends, then scan it from the far edge of the room with Scan & Generate — that is the only test that counts.