QR

Before Generating

1. Choose correct type — URL is not the only option. See types.md for vCard, WiFi, email, SMS, geo, etc.
2. Shorten dynamic URLs — Long URLs = dense codes = harder to scan. Use short links for tracking too.
3. Set error correction — L (7%) for clean environments, M (15%) default, Q (25%) with logos, H (30%) for harsh conditions

Sizing Rules

Minimum sizes by scan distance:

• Phone at arm's length (~30cm): 2x2 cm minimum
• Table tent (~50cm): 3x3 cm
• Poster (~1m): 5x5 cm
• Billboard (~5m): 25x25 cm

Formula: QR size = scan distance ÷ 10

Color & Contrast

• Minimum 70% contrast between foreground and background
• Dark on light ONLY — scanners expect dark modules
• Never invert (white on black fails on many readers)
• Avoid gradients on modules — solid colors only
• Background can have subtle texture if contrast maintained

Testing Checklist

Before printing/deploying:

• Scan with 3+ different phones (iOS, Android old/new)
• Test in target lighting conditions
• Verify destination loads correctly
• Check at actual print size, not screen preview
• Test after any logo/customization applied

Common Failures

Symptom	Cause	Fix
Won't scan	Too small / low contrast	Increase size, check colors
Scans but wrong content	URL changed after print	Use dynamic QR / redirect
Works on some phones	Over-customized, low error correction	Reduce customization, increase EC
Slow to recognize	Too dense	Shorten URL, reduce data

Use Case Guides

Context	See
Data types (WiFi, vCard, etc.)	types.md
Business deployment patterns	deployment.md