Free Accessibility Tool

WCAG Color Contrast Checker

Check any foreground/background pair against WCAG 2.1 AA and AAA. Live ratio, pass/fail, and a one-click accessible fix.

  • Exact WCAG formula
  • AA + AAA + non-text
  • Runs in your browser
  • Nothing uploaded

Color Contrast Checker

Text size
Large preview text Normal body text — the quick brown fox jumps over the lazy dog.

4.54:1

  • AA
  • AAA
  • UI / Non-text

How to use the Color Contrast Checker

  1. Enter your two colors. Type or pick a text (foreground) color and a background color — hex or rgb().
  2. Set the text size. Choose normal or large text; large text (≥24px, or ≥18.66px bold) has a lower contrast threshold.
  3. Read the verdict. See the exact contrast ratio and whether it passes WCAG AA, AAA, and the 3:1 non-text requirement.
  4. Apply the suggested fix. If the pair fails, click the suggested accessible color to update the text color so it passes.

How to read your contrast result

Enter any two colors above — type a hex value or use the color picker — and this tool computes the exact WCAG contrast ratio between them. The preview shows your colors on real text so you can sanity-check legibility, not just the number.

  • AA (4.5:1 normal / 3:1 large) — the level the ADA is read against in practice, and the one we build to.
  • AAA (7:1 normal / 4.5:1 large) — enhanced contrast; good for body text, not always achievable for brand colors.
  • Non-text 3:1 — for buttons, form borders, icons, and chart colors under 1.4.11.

When a pair fails AA, the tool suggests the nearest color that passes — keeping your hue where it can, only shifting lightness. That keeps your brand recognizable while clearing the bar.

Why color contrast matters so much

Low contrast is the single most common WCAG failure on the web, and it's a frequent trigger in ADA website lawsuits. It affects people with low vision, color vision deficiency, and anyone using a screen in bright sunlight. Because it's easy to measure, it's also easy for a plaintiff's tester to document — which is exactly why fixing it early is high-leverage.

Contrast is necessary but not sufficient. To see what your colors look like to someone with color blindness, try the color blindness simulator. To build a whole palette that passes from the start, use the accessible palette generator.

Frequently asked questions

What contrast ratio do I need to pass WCAG?

For normal text, WCAG 2.1 AA requires a contrast ratio of at least 4.5:1. Large text (≥24px, or ≥18.66px bold) needs 3:1. The stricter AAA level wants 7:1 for normal and 4.5:1 for large text. User-interface components and meaningful graphics need 3:1 under 1.4.11 Non-text Contrast.

How is the contrast ratio calculated?

It's the ratio of the relative luminance of the lighter color to the darker one: (L1 + 0.05) / (L2 + 0.05). Relative luminance is computed from the sRGB channels after gamma-correction. This tool uses the exact WCAG formula, so a result of 4.5:1 here means 4.5:1 everywhere.

Does contrast apply to disabled buttons or placeholder text?

Disabled controls are exempt from the text-contrast requirement, but relying on low-contrast placeholder text as a label is a common failure — placeholders disappear on input and often fail 4.5:1. Use a real, visible form label instead.

Is passing a contrast checker enough to be accessible?

No. Contrast is one of ~50 WCAG 2.1 AA success criteria. It's the most common failure, so it's a great place to start — but keyboard access, screen-reader semantics, focus order, and more all matter. Automated tools catch only about 30–40% of issues; a manual audit covers the rest.

A scan is the start, not the finish

Automated tools catch only 30–40% of WCAG issues. Get a free human-led scan and a real remediation plan that makes your site defensibly compliant.