Understanding QR codes
A Quick Response (QR) code stores text or a link that a camera can read. Common uses include restaurant menus, Wi-Fi sign-ins, tickets and business cards. A QR code stores information in a grid of dark and light squares that a phone camera can read in a fraction of a second. This generator creates codes in your browser, so nothing you type is sent anywhere.
What you can put in a QR code
- Links and text: any URL or plain text. Include
https://so phones open it as a link. - Wi-Fi: uses the
WIFI:T:WPA;S:name;P:password;;format. Scanning it offers to join the network without typing the password. - Email: a
mailto:link that opens a new message with the address, subject and body filled in. - Phone: a
tel:link that offers to call the number. - SMS: an
SMSTO:code that opens a text message to the number with your message ready to send.
Error correction levels
QR codes contain extra data so they can still be read when part of the code is dirty, damaged or covered. Higher levels survive more damage but need more modules, so the code gets denser.
| Level | Recovers up to | Good for |
|---|---|---|
| L | 7% | Screens and clean prints, longest content |
| M | 15% | General use (the default) |
| Q | 25% | Outdoor signs, stickers that get scuffed |
| H | 30% | Codes with a logo placed over the middle |
Checking that a code scans
- Keep strong contrast. Dark modules on a light background are the safest choice.
- Leave a quiet zone. The QR standard asks for a margin of 4 modules around the code. Less can work on a plain background, but not next to busy artwork.
- Print it big enough. A rough rule is that the code should be at least a tenth of the scanning distance, so 2.5 cm (1 inch) across for scanning from 25 cm away.
- Shorter content makes a less dense code that scans more easily. Use a short URL if the link is long.
- Use SVG for print. It stays sharp at any size, while PNG is better for websites and documents.
- Always test the final printed code with a couple of different phones.
