Contrast checker.

Light grey text on a white background is the most common accessibility failure on the web, and it is almost always a deliberate design choice made on a good monitor in a well-lit room. On a phone in sunlight, by someone over fifty, that same text is unreadable. Around one person in twelve has some form of colour vision deficiency, and far more have simply ageing eyes.

WCAG 2.1 sets the thresholds: 4.5:1 for normal text and 3:1 for large text at AA, rising to 7:1 and 4.5:1 at AAA. Large means 24px, or 19px if bold. AA is the level referenced by most accessibility legislation, including the European Accessibility Act, which since June 2025 applies to a wide range of commercial websites and e-commerce in the EU.

The preview here shows both sizes together, because a pair that passes for headlines routinely fails for body copy — and body copy is where nearly all of your actual text lives.

Worth knowing

• Test your real body text size, not just headings. Small text is where contrast pairs fail.
• Do not forget placeholder text, disabled states, and text over photographs. Those are the usual gaps.
• Interactive elements — buttons, form borders, icons — need 3:1 against their surroundings, not just their text.