QR code generator

QR (Quick Response) is a type of 2D barcode invented in 1994 by Denso Wave. It can store up to ~3,000 alphanumeric characters. The black-and-white square modules encode the data, and three finder patterns in the corners allow it to be read in any orientation.

QR codes have four error correction levels based on Reed-Solomon codes: L (7%), M (15%), Q (25%) and H (30%). The percentage indicates how much of the code can be damaged or obscured and still be read. If you plan to print the QR on a surface or embed a logo on top, use level H.

It depends on the correction level and the data type. For alphanumeric text at level M: up to ~2,300 characters. For short URLs (under 100 characters) the QR will be small and dense. The more content, the higher the module density and the harder it is to scan at small sizes — use shortened URLs for printed QR codes.

For paper printing, a 256×256 px QR is fine for on-screen or digital use. For print quality, use at least 512×512 px or, better, 1024×1024 px for large formats (posters, cards, packaging). The recommended minimum printed size is 2×2 cm — below that, phone scanners struggle to read them.