QR Code Generator

How QR codes encode your data

A QR code is a 2D matrix barcode defined by the ISO/IEC 18004 standard. Unlike a 1D barcode, which is a single row of bars, a QR code stores data across a grid of black and white squares called modules. The three large squares in the corners are finder patterns that let a scanner locate and orient the code even when the photo is rotated or skewed. The rest of the grid carries your data plus error-correction information.

Versions and sizes

QR codes come in 40 versions. Version 1 is a 21×21 grid; every step up adds four modules to each side, reaching 177×177 at version 40. A bigger version holds more data but needs more physical space and a sharper camera to read. This generator picks the smallest version that fits your content automatically — so the less you encode, the simpler and more reliable the code.

Error-correction levels L, M, Q, H

QR codes use Reed-Solomon error correction, which is why a code still scans with part of its surface dirty, torn, or covered. You trade data capacity for resilience across four levels: L recovers ~7% of damage, M ~15%, Q ~25%, and H ~30%. Higher levels reserve more of the grid for recovery data, so the same content produces a denser code. Pick H for codes printed on packaging or with a logo overlay; pick L only when you must squeeze maximum data into a small symbol.

What kind of data fits

QR codes have four encoding modes — numeric, alphanumeric, byte (UTF-8), and kanji — chosen automatically based on your input. Numeric data is the most compact (up to ~7,089 digits), alphanumeric is next (~4,296 characters), and arbitrary UTF-8 text is the least dense (~2,953 bytes). A QR code is just a string, so the convention is that scanner apps recognise prefixes: https:// opens a link, mailto: drafts an email, tel: dials a number, and plain text is shown as-is. To check what an existing code already holds before you scan it on your phone, you can decode a QR code from an image or your camera first.

The quiet zone matters

The blank margin around a QR code — the quiet zone — is part of the spec, not decoration. The standard calls for a margin of at least four modules. Cropping it tight or placing the code against a busy background is one of the most common reasons a code fails to scan. Keep the margin set to 2 or more here and leave clear space around it when you place it.

Encoding something more specific?

This generator handles any plain string, but several payload types have a dedicated tool that builds the exact prefix and escaping for you. If your goal is to connect guests to WiFi, share a contact, or trigger a text message, start with the purpose-built version rather than hand-typing the format here.

• • WiFi QR code generator — assembles the WIFI: credential string so a scan offers a one-tap join.
• • vCard QR code generator — wraps name, phone, and email in a BEGIN:VCARD block your phone can save.
• • QR code decoder — go the other way and read what an existing code holds before you act on it.