WCAG Contrast Checker

The WCAG (Web Content Accessibility Guidelines) define contrast standards to ensure text is readable for people with visual disabilities. Contrast is calculated as the ratio between the luminance of the lighter color and the darker color, ranging from 1:1 (no contrast) to 21:1 (white on black).

WCAG 2.1 Level AA requires: 4.5:1 for normal text, 3:1 for large text (≥18pt or ≥14pt bold) and UI components. Level AAA requires: 7:1 for normal text, 4.5:1 for large text.

To increase contrast: darken the text (use black or dark grey instead of light grey), lighten or darken the background, avoid colors with similar luminosity values. Tools like WCAG Contrast Checker or browser DevTools can highlight problem areas.

Level AA asks for 4.5:1 on normal text and 3:1 on large text and interface components. Level AAA rises to 7:1 on normal text and 4.5:1 on large text.

The contrast ratio comes from the relative luminance of the two colors: lighter luminance plus 0.05, divided by darker luminance plus 0.05. Values run from 1:1 to 21:1, which is black on white.

The WCAG count text as large from 18pt upwards, or from 14pt when bold. Large text only needs a ratio of 3:1 for level AA, against the 4.5:1 asked of normal text.

Yes, and not because we promise it: this tool runs entirely inside your browser. What you type or upload never leaves your device, so it never reaches a server of ours and there is nothing we could keep, read or lose. You can check it yourself: open the page, disconnect from the internet, and the tool keeps working.

No. There is no database behind this tool: we do not store your files, your text or your results. When you close the tab nothing is left — not here with us, because it never arrived, and not anywhere else.

We do not profile you: there is no account to create, we never ask for your email to use a tool, and we keep no profile of what you do. We are an Italian company and we work under the GDPR and the other European rules, with the privacy notice and the consent request in plain sight. One thing we say in full rather than hiding it behind a slogan: the ads on the page are Google's, and Google may use cookies to personalise them. You decide from the consent banner: if you say no the ads stay, but they are not personalised, and the tool works exactly the same.

From the ads on the page, and that is all. We do not sell your data, there is no hidden paid plan, there is no limit that eventually asks for your card, and you do not have to sign up. The ads pay for the servers and for the time we spend writing the tools: that is how we can keep them open to everyone.