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Website glossary· Readable for everyone

What is colour contrast?

Colour contrast is the difference in lightness between text (or a button) and the colour behind it, measured as a ratio from 1:1 to 21:1.

Why it matters for a small business site

Low-contrast text is hard to read for people with low vision, for many older visitors and for anyone using a phone in sunlight. If people can’t read your offer or find your button, nothing else on the page matters.

How to check yours

  1. Put your text colour and background colour into a contrast checker, such as WebAIM’s, to get the ratio.
  2. Check the hard cases: light grey text, text on photos, white text on your brand colour, and placeholder text in forms.
  3. Look at the page on a phone outdoors.

What good looks like

At least 4.5:1 for normal text and 3:1 for large text (about 24px, or 19px bold): the WCAG AA level. Button edges, form field borders and icons people need should reach 3:1 against what’s around them.

Common mistakes

  • Light grey body text on white because it “looks cleaner”.
  • White text on a pale brand colour such as yellow, light orange or mint.
  • Text placed over photos without a darker layer behind it.
  • Meaning shown only by colour, like an error in red with no icon or words.
Free site audit

See how your current site does

The free audit checks contrast on your first screen against the WCAG AA level, for body text and for your main button, and names the colours that fall short.

One page · the first screen · design, contrast, wording

Printed big on the certificate, with the site's address under it. Plain text — links are removed.

Free · no sign-up · one page, above the fold

This is the simple audit. Advanced audits check up to 20 pages, pages behind a login, and flows walked by AI — with an account on Pro.

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