QR code glossary · Anatomy of a QR code
Quiet zone
Also called: Margin, Clear zone
Definition
The quiet zone is the blank margin that must surround a QR code on all four sides so a scanner can tell where the code begins; ISO/IEC 18004 requires it to be at least 4 modules wide for a regular QR code and 2 modules for a Micro QR code.
How it works
A scanner finds a QR code by looking for the dark-light-dark-light-dark sequence of a finder pattern. Each finder pattern sits right at the edge of the code, so the scanner needs plain light space outside it to see where the pattern starts. Text, a photo or a frame pressed against the code merges with that outer dark ring and hides the pattern.
- Quiet zone
The quiet zone is measured in modules, not millimeters, so it grows with the code: a code with larger modules needs a wider margin. It must be the same light color as the code’s light modules. It does not have to be white, but it has to be plain.
Why it matters
A missing quiet zone is one of the most common reasons a well-made code fails in print. Typical causes are a designer cropping the image tight, a code placed flush against the edge of a photo or a colored panel, text set too close, and stickers die-cut right at the code’s edge.
Many phone decoders cope with a narrower margin in good light, but that is not guaranteed, and the standard asks for 4 modules. Keep the full margin, count it as part of the space the code needs, and make sure nothing in the layout intrudes on it.
Example
A version 3 code (29 modules) printed 2.5 cm wide has modules of about 0.86 mm, so its quiet zone is about 3.5 mm on each side, and the code needs a clear square of roughly 3.2 cm in total.
In CirculateQR
Every code CirculateQR renders or exports keeps a quiet zone of at least 4 modules (the free generator lets you widen it to 8). AI art is the exception, because there the code is painted into the picture.
Related terms
- ModuleA module is a single square cell of a QR code, either dark or light, and the basic unit of the symbol: each one is a bit of data or part of a fixed pattern, and the printed width of one module decides how far away the code can be read.
- Finder patternA finder pattern is one of the three large concentric squares in the top-left, top-right and bottom-left corners of a QR code, which a scanner uses to detect the code, measure its size and angle, and work out which way up it is.
- Micro QR codeA Micro QR code is a smaller variant of the QR code, defined in the same standard (ISO/IEC 18004), that uses a single finder pattern and a 2-module quiet zone to fit up to 35 digits in a symbol of 11 × 11 to 17 × 17 modules.
- Contrast ratioContrast, for a QR code, is the difference in brightness between its dark and light modules; scanners need a large difference, with the dark modules darker than the light ones, and designers often check it with the WCAG contrast ratio, which runs from 1:1 (no difference) to 21:1 (black on white).
- AI QR code artAI QR code art is an image made with a generative AI model so that a working QR code is part of the picture, with the code’s dark and light modules formed by elements of the scene instead of plain squares.
Learn more
- QR code size guide: Sizes, margins and print checks.
- Free QR code generator: Set the quiet zone from 4 to 8 modules.
Sources
Last updated . Written by the CirculateQR team; technical facts follow the sources listed above. Example codes and sizes are computed with the open-source qrcode encoder that CirculateQR uses. Spotted something wrong? Email support@circulateqr.com. QR Code is a registered trademark of DENSO WAVE INCORPORATED.
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