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Barcode size, quiet zone & resolution done right

Whether a barcode scans reliably rarely depends on its content – it depends on size, quiet zone, contrast and print resolution. This guide sums up the key rules in a practical way.

Minimum size & scaling

Retail barcodes such as EAN-13 are printed between 80–200 % of the nominal size – below 80 % you get read errors at the till. 2D codes like the QR code should be at least about 2 × 2 cm so cameras can focus reliably.

Quiet zone

Every barcode needs an empty margin. For EAN/UPC that is at least 10× the narrowest module width on the left and right; for QR codes at least four modules all around. Without the quiet zone, decoding fails.

Resolution & DPI

For printing, at least 300 dpi is recommended. Vector formats such as SVG or PDF are safest because they scale without loss. See the guide how to print barcodes.

Contrast & colours

Dark bars on a light background give the best contrast. Avoid inverted colours, glossy films and metallic backgrounds – the red laser light of many scanners struggles with them.

Common mistakes

Scaling too small, a missing quiet zone, blurry print and JPEG compression are the most common causes of unreadable codes. Print a sample and test it before a production run.

Related generators

FAQ

What is the minimum size for an EAN-13?

About 80 % of the nominal size (roughly 29.8 × 20.7 mm). Below that, read errors at the checkout increase significantly.

How wide must the quiet zone be?

For EAN/UPC at least 10× the module width on the left and right; for QR codes at least four modules all around.

PNG or SVG for printing?

SVG and PDF are resolution-independent and safest for printing. Use PNG only at sufficient resolution (at least 300 dpi).