How big can a QR code logo be before it stops scanning?

Why 30% is not a logo allowance

DENSO WAVE describes error correction in terms of restoration of total codewords, not a percentage of the image that can safely be covered. A codeword is a unit of encoded data. You cannot turn the level H recovery figure into a promise that a logo may hide 30% of the squares.

The finder squares, timing lines and alignment patterns help a reader locate and interpret the symbol. Keep them unobstructed rather than relying on error correction to compensate. The placement of covered modules and the distribution of affected codewords matter; there is no fixed area threshold that works for every payload, QR version and reader.

The DENSO WAVE FAQ warns that overlaying an illustration can make reading impossible or slow. Higher error correction does not certify a branded design. It can also increase the symbol's data density or required size.

Width and area are different

For a square logo on a square symbol, a width of 40% means an area of 16%. That is geometry, not a scanning limit. Count the entire obscured region, including any background pad, and measure against the symbol itself rather than its surrounding margin.

A width under a third is sometimes used as a starting rule, but it is not a verified safe maximum. A smaller mark can still cover a structural pattern. If reliability matters more than an embedded logo, place the brand beside the code.

What the logo setting means

A library's image-size setting is not necessarily a percentage of visible code area. QR Codes Made Easy uses a fixed logo setting and selects error correction level H when you add an image. Those implementation choices limit the design; they do not prove that every resulting code will scan.

Placement and print-proof checklist

1. Choose placement deliberately. A centered logo avoids the corner finder squares only while it stays small enough, and can still cover alignment patterns. Project Nayuki's QR implementation places alignment patterns according to version; version 7 includes an alignment pattern in the center. There is no universally empty center reserved for artwork.
2. Keep the obscured area small. A light pad may separate the logo visually, but it also hides modules. Include it when judging coverage. This tool uses level H with a logo; that adds error-correction capacity, not a guarantee.
3. Preserve contrast and the quiet zone. Use a dark code on a uniform light background. DENSO WAVE specifies a four-module clear margin on every side of a standard QR symbol. Keep adjacent logos, text and borders outside that margin.
4. Check the exported file. Decode the actual PNG or SVG you will supply to the printer, and confirm its destination or data. A clean on-screen decode is a useful check, not proof of print reliability.
5. Test a printed proof. Print the final layout at its intended physical size, on the intended stock and finish when possible. Try more than one phone, including iPhone and Android, at the expected distance, angles and lighting. Check that each opens the intended destination. Retest after changing the logo, size, payload, colors or layout.

DENSO WAVE's module-size guidance explains why printer resolution and reader limits both matter. A screen cannot reproduce ink spread, glare or a curved label. Use the print-size guide to plan the proof, and keep the pre-print checklist handy before a full run.

FAQ