QR Codes Explained: How They Work and How to Make One

QR codes appear on menus, posters, packaging, tickets and payment screens. A QR code is simply a two-dimensional barcode that stores data a phone camera can read in a fraction of a second. Knowing a few basics helps you create codes that work first time.

How a QR code works

A QR (Quick Response) code is a grid of black and white squares called modules. Three large squares in the corners let a scanner detect position and orientation, a smaller alignment pattern corrects for perspective, and the remaining modules hold your data plus error-correction information. Because the data is redundant, a code can often still be read when part of it is dirty or covered.

What you can store in a QR code

• Website URLs and landing pages
• Plain text and notes
• Wi-Fi credentials so guests can join with one scan
• Contact details (vCard) and email or SMS shortcuts
• Payment links and app download links

Static vs dynamic QR codes

A static QR code encodes the destination directly. It never expires and needs no account, but you cannot change where it points after printing. A dynamic QR code encodes a short redirect link that can be edited later and often provides scan analytics, but it depends on the service staying online. For printed materials with long lifespans, a static code that links to a URL you control is usually the safest choice.

Error correction levels

• Level L recovers about 7 percent of damaged data
• Level M recovers about 15 percent
• Level Q recovers about 25 percent
• Level H recovers about 30 percent, useful if you plan to place a logo in the centre

Higher error correction makes the pattern denser, which means each module is smaller at a given print size. Pick the lowest level that suits the environment.

Design tips for reliable scanning

1. Keep strong contrast: dark modules on a light background scan best, and inverted codes are not supported by every reader.
2. Leave a quiet zone, a blank margin of at least four modules, around the code.
3. Print at a sensible size. As a rule of thumb, scanning distance should be roughly ten times the width of the code.
4. Shorten long URLs, since less data means a simpler and more robust pattern.
5. Always test with at least two different phones before printing in bulk.

Staying safe with QR codes

Scammers sometimes paste malicious QR stickers over genuine ones. Check the URL preview your phone shows before you open it, be cautious with codes that ask for logins or payments, and avoid scanning codes from unsolicited messages. When you publish codes, place them where they cannot easily be tampered with.

Create a QR code in seconds

Enter your URL or text in a QR code generator, preview the result, and download it as an image. Test the code before sharing it.