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QR Code Generator

Generate QR codes from text or URLs

What is a QR Code?

A QR Code (Quick Response Code) is a two-dimensional barcode invented by Masahiro Hara at Denso Wave in 1994. Originally designed for tracking automotive parts during manufacturing, QR codes can now store URLs, plain text, contact information (vCards), WiFi credentials, and more. They are read by smartphone cameras or dedicated barcode scanners, making them one of the most versatile tools for bridging physical and digital information.

How QR Codes Work

QR codes encode data in a grid of black and white square modules. Three large squares in three of the four corners serve as position detection patterns, allowing the scanner to determine the code's orientation, angle, and size. The remaining area contains data modules, error correction codewords, format information, and timing patterns that help the scanner synchronize its reading.

Error Correction Levels

QR codes use Reed-Solomon error correction, available at four levels:

  • L (Low): ~7% of codewords can be restored
  • M (Medium): ~15% recovery — recommended for most general-purpose use
  • Q (Quartile): ~25% recovery — good for marketing materials
  • H (High): ~30% recovery — use when codes might be partially damaged or obscured

Higher error correction means the QR code can survive more damage, but it also reduces the amount of data the code can hold.

Common Mistakes

  • ✗Using low-contrast colors — always maintain at least a 4:1 contrast ratio between foreground and background
  • ✗Forgetting the quiet zone — leave at least four module widths of blank space around the QR code
  • ✗Overloading data in a single code — keep URLs short and concise for faster, more reliable scanning

Pro Tips

  • ✓Use error correction level H (~30% recovery) for codes that might be partially damaged or printed on rough surfaces
  • ✓Test your QR code with multiple phones and apps before committing to a large print run
  • ✓Shorten URLs before encoding to produce simpler, smaller QR codes that scan more reliably

Real-World Examples

Restaurant menus

Link QR codes to digital menus — level Q error correction handles table smudges

Event tickets

Encode unique ticket IDs with level H correction for reliable gate scanning

Business cards

Use vCard QR codes at minimum 2cm x 2cm for close-range smartphone scanning

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QR Codes & Barcodes

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About QR Code Generator

What is a QR Code?

A QR Code (Quick Response Code) is a two-dimensional barcode that encodes data in a square grid. Unlike traditional barcodes (which are one-dimensional), QR codes can store much more data -- up to 4,296 alphanumeric characters -- and can be scanned from any angle. They're used everywhere: restaurant menus, event tickets, business cards, product packaging, and WiFi login screens.

QR codes use Reed-Solomon error correction at four levels. This tool generates at Level H (High, ~30% recovery), which means the code still scans even if partially damaged or obscured. For most use cases this is overkill in a good way -- it maximizes reliability.

QR Code Best Practices

Use short URLs. Shorter input produces simpler QR codes with fewer modules, which scan faster and work at smaller sizes. Consider a URL shortener for very long links, but be aware the QR code breaks if the shortening service goes down.

Mind the quiet zone. The blank margin around the QR code should be at least four modules wide on all sides. Without it, scanners can't detect the position patterns.

Ensure contrast. Black on white is always reliable. If you customize colors, maintain at least a 4:1 contrast ratio between foreground and background.

Test before printing. Scan with multiple phones and apps before a large print run. Check from the expected viewing distance and under typical lighting.

Size for distance. For close-range scanning (business cards, flyers), 2 cm x 2 cm is the minimum. For billboards or posters meant to be scanned from meters away, scale up proportionally.

This utility is provided for informational purposes only. KnowKit is not responsible for any errors in the output.

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QR Code Generator FAQ

How much data can a QR code store?

The maximum capacity depends on the QR code version (1-40) and error correction level. At the lowest error correction (L), a Version 40 QR code can hold up to 7,089 numeric digits, 4,296 alphanumeric characters, or 2,953 bytes of binary data. Higher error correction levels reduce data capacity. Keep your data concise for faster, more reliable scanning.

Do QR codes expire?

No, the QR code image itself never expires. Once generated, it will always encode the same data. However, if the QR code contains a URL, that URL could stop working if the website changes, the server goes offline, or the domain expires. Static QR codes (like those generated here) encode the data directly and cannot be updated after creation.

Can QR codes be colorful?

Yes, QR codes can use custom colors, but you must maintain high contrast between the foreground modules and the background. Dark foreground on a light background works best. Some contrast loss is acceptable if you use a higher error correction level (Q or H), which provides redundancy. Always test a colored QR code with multiple scanners before distributing it.

What's the minimum size for a printable QR code?

A general rule is that the scanning distance should be approximately 10 times the QR code's width. For a typical smartphone scanning distance of 30 cm (12 inches), the QR code should be at least 3 cm (1.2 inches) wide. For business cards, 2 cm x 2 cm is the practical minimum. Always test print a sample before committing to a large print run.