QR Code Best Practices — Size, Error Correction, and Design Tips

QR codes are everywhere — menus, packaging, business cards, event tickets. But a surprising number of them don’t scan reliably. Here’s how to avoid that.

Minimum Size for Reliable Scanning

The general rule: a QR code should be at least 2 cm × 2 cm (about 0.8 inches) for close-range scanning (within 30 cm). For every additional 30 cm of scanning distance, double the size.

A practical formula:

QR code size = scanning distance / 10

Example: scanning from 1 meter away
Size = 1000 mm / 10 = 100 mm (10 cm)

On screens, ensure the QR code is at least 240 × 240 pixels. Smaller codes work on high-DPI screens but fail on lower-resolution displays.

Error Correction Levels

QR codes have built-in redundancy that allows them to be read even when partially damaged or obscured. There are four levels:

• L (Low) — recovers up to 7% damage. Smallest code, best for clean digital displays.
• M (Medium) — recovers up to 15% damage. Good default for most uses.
• Q (Quartile) — recovers up to 25% damage. Use for printed materials that may get scuffed.
• H (High) — recovers up to 30% damage. Required if you want to place a logo over the code.

Higher error correction means more modules (black/white squares), which makes the code denser and harder to scan at small sizes. Use the lowest level that fits your scenario.

Adding a Logo Safely

Placing a logo in the center of a QR code is popular but risky if done wrong:

• Always use error correction level H (30% recovery)
• Keep the logo under 20% of the total QR code area
• Center the logo — the three corner finder patterns must remain fully visible
• Add a small white border around the logo so it doesn’t blend into the code
• Test on at least 3 different phone models after adding the logo

Content and URL Tips

• Use short URLs. Longer data means a denser QR code. Use a URL shortener or a redirect if the target URL is long.
• Use a redirect URL you control. If you print QR codes on physical material, you can’t update them later. Point to a URL you can redirect, like yoursite.com/qr/menu.
• Prefer HTTPS. Some browsers warn users about non-HTTPS links, which kills trust.
• Uppercase URL text for smaller codes. QR codes have a special alphanumeric mode that’s more efficient with uppercase letters and numbers.

The Quiet Zone

QR codes need a white border (quiet zone) of at least 4 modules wide on all sides. Without it, scanners can’t distinguish where the code ends and the background begins. This is the most common reason codes fail to scan.

Testing Checklist

• Scan with the native camera app on both iOS and Android
• Test at the actual intended distance (not just close-up)
• Test in low light and bright sunlight
• If printed, test on the actual printed material (paper, sticker, fabric)
• Verify the destination URL loads correctly on mobile

Related Tools

• QR Code Generator — create customizable QR codes with error correction options
• Image Compressor — optimize QR code images for web and print