Type anything and watch a real QR code being built, one step at a time - from the size of the grid to the last format bit. Hover or tap any square to see what it does.
It runs on the same engine as our QR Code Generator, so what you see is exactly how your codes are made. Got a code you want to test? Grade it with the QR Code Checker.
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Hover or tap a square to see what it is.
| Part | Where | What it does |
|---|---|---|
| Finder patterns | 3 corners | Tell the scanner where the code is, how big it is and which way up |
| Timing patterns | Row 6 and column 6 | Alternating squares that give the scanner the grid size |
| Alignment patterns | Version 2 and up | Keep the grid straight when the code is curved or tilted |
| Format info | Around the finders | Error correction level and mask number, stored twice |
| Version info | Version 7 and up | The version number, stored twice |
| Data | Everywhere else | Your text, as bits |
| Repair data | After the data | Reed-Solomon codewords that rebuild damaged parts |
The white border around the code - the quiet zone, 4 modules wide - is part of the standard too. Crop it and many phones stop reading the code.
The QR code was invented in 1994 by Masahiro Hara and his team at Denso Wave, a Toyota group company, to track car parts on the factory floor. Barcodes held too little and had to be scanned one by one; "QR" stands for Quick Response.
The team surveyed printed matter to find the ratio of dark and light least likely to appear by chance - 1:1:3:1:1 - and used it for the finder patterns. Denso Wave patented the code but chose not to enforce the patent, which is a big reason QR codes are everywhere today. The format became the ISO/IEC 18004 standard.
Read the full story, with the anatomy explained square by square, in our guide how QR codes work. Barcodes have their own history - the first product scanned at a till was a pack of Wrigley's gum in 1974 - told in barcode types explained.
Your text is turned into bits - ones and zeros - and every dark square is a 1, every light square a 0. The bits are packed into bytes called codewords, extra repair codewords are added, and the whole stream is laid out in a zig-zag path from the bottom-right corner.
Step through the explainer above to see each stage with your own text. The full story, with history and diagrams, is in our guide on how QR codes work.
Those are the finder patterns. Their 1:1:3:1:1 rhythm of dark and light is rare in normal pictures, so a scanner spots them fast, from any angle. Three corners are enough to know where the code is, how big it is and which way up it sits - the missing fourth corner gives away the rotation.
Yes. Every QR code carries Reed-Solomon repair data. At level L it can rebuild about 7% of the code, at M 15%, at Q 25% and at H 30%. That is also why a logo in the middle works - the hidden squares are rebuilt from the repair data.
Want to see how much repair data a real code already uses? Drop it into the QR Code Checker for a damage map.
After the data is placed, the code is flipped by one of 8 simple patterns (checkerboards, stripes, diagonals) so that it never ends up with big blank areas or shapes that look like a finder pattern. The encoder tries all 8, scores each one, and keeps the lowest score. The mask number is stored in the format info, so the scanner can undo it.
The biggest QR code, version 40 at level L, holds up to 7,089 digits, 4,296 letters and numbers (capitals only) or 2,953 bytes of any text. In practice, keep codes short - fewer squares mean bigger squares and faster scans. The QR Code Generator can shrink long links for you.
A barcode stores data in one direction - the width of the bars - so it holds a short number like a product code. A QR code is a 2D code: it uses both directions and holds whole links, WiFi logins or contact cards, with built-in repair data.
Need a product, book or shipping barcode? Use the Barcode Generator, and read about the types in barcode types explained.
