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QR code guide

What QR codes are and how to use them effectively.

What is a QR code?

A QR code (Quick Response code) is a two-dimensional barcode that encodes data — most commonly a URL — as a matrix of black and white squares. Created by the Japanese company Denso Wave in 1994, QR codes became ubiquitous after smartphones with cameras made scanning trivial. Unlike a traditional barcode (1D), a QR code encodes data in both dimensions, allowing far more information in a smaller space.

PNG vs SVG: which format should you download?

The choice depends entirely on how you intend to use the QR code:

• PNG is a raster image. It has a fixed pixel dimension (256, 400, or 600 px depending on your size selection). Use PNG for digital use — embedding in web pages, presentations, emails, and social media posts where you know the display size. Avoid scaling PNG significantly above its native size or the QR code will appear blurry and may fail to scan.
• SVG is a vector format. It scales to any size without losing sharpness — from a business card to a billboard. Use SVG for any print application: flyers, posters, packaging, banners, and signage. Most professional design software (Adobe Illustrator, Figma, Affinity Designer, Inkscape) imports SVG natively.

Understanding error correction levels

QR codes include redundant data so they can still be read even when partially damaged, obscured, or dirty. The four error correction levels trade off code size against resilience:

• L (Low, 7%): Can recover from up to 7% data loss. Produces the smallest, densest-looking code. Good for clean digital displays where damage is unlikely.
• M (Medium, 15%): The standard for most applications. Balances code size and resilience. Choose M unless you have a specific reason not to.
• Q (Quality, 25%): Better for printed materials that may accumulate minor scratches or dirt over time.
• H (High, 30%): Maximum resilience. Use H when you plan to overlay a logo or design element on top of the QR code. This level allows up to 30% of the code to be obscured while remaining scannable.

Best practices for QR codes that always scan

• Quiet zone: Every QR code requires a white border (quiet zone) around it — at least four modules wide. If you're adding the QR code to a coloured background, ensure there's sufficient white padding.
• Minimum size: A QR code smaller than about 2 cm × 2 cm (0.8 in × 0.8 in) in print is difficult to scan reliably. If in doubt, go larger.
• Contrast: Dark modules on a light background. Never reverse this or use low-contrast colour combinations — most camera apps struggle with non-standard colours.
• Short URLs perform better: Shorter content means fewer modules, which means a less dense, easier-to-scan code. Use a URL shortener for very long URLs.
• Test before you print: Scan the QR code from the preview in at least two different apps (iOS Camera, Google Lens, etc.) before committing to a print run.

What can a QR code encode?

While URLs are the most common content, QR codes can encode many types of structured data that apps recognise automatically:

• URLs: https://example.com/page
• Wi-Fi credentials: WIFI:S:NetworkName;T:WPA;P:password;;
• Email: mailto:name@example.com
• Phone: tel:+15551234567
• SMS: smsto:+15551234567:Your message here
• Plain text: Any text up to ~4,296 alphanumeric characters
• vCard contact: Structured contact data format for instant phone-book saving