From text to code

Paste anything into the content panel: a link, a Wi-Fi password in the right format, a vCard, a plain sentence. The preview redraws as you type, and the badge under it shows the pixel size of the finished image. When you are happy with it, download the PNG.

Nothing is sent anywhere while the code is generated. The image is drawn on a canvas inside the page.

Size, error correction and colour

  • Size runs from 128 to 640 pixels and starts at 320. The number is the width and the height of the downloaded square.
  • Error correction adds redundancy to the code so it still reads when part of it is damaged or hidden. Low recovers about 7 percent, Medium 15 percent, Quartile 25 percent and High 30 percent. Medium is a sensible default; High is worth it for a sticker that will be covered or scratched.
  • Colours set the dark modules and the light background. The contrast between the two is what a scanner reads.

How to use it

  1. Paste the content into the panel. Check the preview before changing anything else — a code that looks wrong here will not look better when it is printed.
  2. If the link carries characters that need escaping, the URL Encoder makes it safe first.
  3. Set the size for where it will be used. A code printed at 2 cm across needs roughly 300 pixels; one going on a wall can be much larger.
  4. Leave the error correction on Medium unless you have a reason to change it.
  5. Keep the colours dark on light. If you change them, check that the dark colour is genuinely darker than the background.
  6. Download the PNG and place it with a clear margin around it.

What decides whether a code scans

  • Contrast. Scanners need a clear difference between the modules and the background. Light grey on white is the classic mistake.
  • Size on the page. The code has to be big enough for the scanner to find it. As a rule of thumb, print it at least 2 cm across, and considerably larger if people will be scanning it from a distance.
  • The quiet zone. The blank border around the code is part of the format. Put the image on a clean background and leave the space around it.
  • Content length. The longer the text, the denser the code becomes. A long URL turns into a block of tiny squares that is hard to scan from any distance.

Good to know

  • A QR code can carry a link, plain text, a Wi-Fi login, a contact card or a location. Most phones switch to the right action once they read it. A contact card or a Wi-Fi string is copied as plain text, and the Text Cleanup tool tidies the stray line breaks they often arrive with.
  • The download is a PNG at the exact pixel size you chose, so there is no resampling when you place it.
  • Shorten long links before encoding them. A dense code is slower to scan and easier to misread.
  • Test the printed code with more than one phone before you print a hundred of them.