QR Codes: How They Work and Best Practices for Use

QR (Quick Response) codes are two-dimensional barcodes that encode data in a grid of black and white squares. They bridge the physical and digital worlds — scan with a phone camera to open a website, connect to WiFi, or save a contact.

How QR codes work: Data is encoded as a pattern of dark and light modules arranged in a square grid. Three large squares in the corners (position detection patterns) help the scanner locate and orient the code. A smaller alignment square helps with perspective correction. The remaining area encodes the actual data with error correction (Reed-Solomon codes) that allows the code to be read even if up to 30% is damaged or obscured.

Data capacity: QR codes can store up to 7,089 numeric characters, 4,296 alphanumeric characters, 2,953 binary bytes, or 1,817 Kanji characters. Longer content produces denser (more complex) codes that are harder to scan reliably.

Best practices: - Keep content concise — under 200 characters for reliable scanning - Ensure adequate contrast: dark modules on a light background - Include a quiet zone (white margin) of at least 4 modules on all sides - Minimum print size: 2 × 2 cm (0.8 × 0.8 in) for close-range scanning - Test with multiple devices (iOS and Android) and in different lighting before printing - For curved surfaces (bottles, cans), increase the size to compensate for distortion

Use Tooler's QR Code Generator to create SVG QR codes that scale to any size without pixelation.