QR Code Generator: What They Store, How They Work, and When to Use Them
QR codes (Quick Response codes) are two-dimensional barcodes that can store significantly more data than traditional 1D barcodes. A standard QR code can hold up to 7,089 numeric characters, 4,296 alphanumeric characters, or 2,953 bytes of binary data.
What You Can Encode
URLs (most common): Any web address. The scanner opens the URL in the device browser. Length matters — shorter URLs generate simpler (less dense) QR codes that scan more reliably.
Plain text: Notes, instructions, product information. Up to ~4,000 characters for basic text.
Contact information (vCard format): Name, phone, email, address — scannable directly into phone contacts.
WiFi credentials: Network name (SSID), password, and security type. Scanning automatically connects the device. Highly practical for guest access.
Email: Pre-filled email to a specific address with optional subject and body.
Phone number: Opens the phone app ready to call.
SMS: Opens messaging app with pre-filled number and optional text.
Calendar event: Creates a calendar entry with title, date, time, and location.
Error Correction Levels
QR codes have four error correction levels (L, M, Q, H) that allow the code to be readable even if partially damaged:
- Level L: recovers 7% data loss — smallest, densest code
- Level M: recovers 15% — standard for most uses
- Level Q: recovers 25% — good for codes that might get damaged
- Level H: recovers 30% — largest code, use when durability matters
For printed marketing materials: use level H. For digital display: level M is sufficient.
Size and Scanning Distance
A QR code needs to be at least 2×2 cm to scan reliably at typical smartphone distances. For outdoor signage meant to be scanned from 5+ feet: minimum 8×8 cm. Larger is always better.
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