QR Code builder
Make a QR Code for a link, a Wi-Fi network, a contact and more, then see how the code is built.
Anatomy of this QR Code · version 2 · 25×25 modules
- Finder patternsThe three big squares let a scanner find the code, measure its size and work out which way up it is.
- SeparatorsA one-module white border around each finder so it stands apart from the data.
- Timing patternsAlternating dark and light modules between the finders give the scanner the module grid.
- Alignment patternsSmaller squares (version 2 and up) that correct for curved or tilted surfaces.
- Format informationError-correction level and mask pattern, written twice for safety, protected by its own BCH code.
- Version informationFrom version 7 up, the version number is written twice near the corners.
- Dark moduleA single module that is always dark, beside the bottom-left finder.
- Data and error correctionEverything else: your message plus Reed–Solomon codewords that let a damaged code still read.
How QR Codes work
A QR Code is a grid of square modules. Three finder squares in the corners let a camera locate it at any angle; timing lines set the grid; alignment squares correct for curved surfaces. The rest holds your data, split into 8-bit codewords and interleaved with Reed–Solomon error-correction codewords, then masked with one of eight patterns so the code has no large blank or solid areas.
Error correction is the trade-off you choose above: level L recovers about 7% damage and makes the smallest code; level H recovers about 30%, enough to cover the middle with a logo.