Colour Contrast
WCAG Testing.
Ensure your website is accessible to everyone. Check text and background colour combinations against WCAG 2.1 AA and AAA relative luminance standards.
Text Colour
Background Colour
Contrast Ratio
4.47:1
Poor contrast — hard to read.
Live Preview
Large Text Preview
This is normal text. It should be easy to read and comfortable for long-form content. Ensuring high contrast protects visually impaired users.
Normal Text
< 18pt regularLarge Text
≥ 18pt or 14pt boldHow It Works
Test your colour palette for accessibility instantly.
Select Colours
Enter a hex code or use the colour picker for your text and background colours. The tool supports real-time editing.
Check Contrast Ratio
The tool automatically calculates the relative luminance and displays the precise contrast ratio.
Verify Compliance
Instantly see if your combination passes WCAG 2.1 AA and AAA standards for normal and large text sizes.
The Complete Guide to WCAG Colour Contrast in 2026
Digital accessibility is no longer optional. According to the World Health Organization, over 2.2 billion people globally have a vision impairment. Designing with adequate colour contrast ensures that your text, UI components, and graphical elements are usable by everyone. Furthermore, many countries legally mandate adherence to WCAG 2.1 AA standards for commercial and public sector websites.
What is Contrast Ratio?
It is a mathematical formula measuring the difference in relative luminance between two colours. It ranges from 1:1 (no difference, e.g., white on white) to 21:1 (maximum difference, e.g., black on white). High contrast makes reading effortless.
The 'AA' Standard
This is the global benchmark for accessibility. To pass AA, normal text (under 18pt) requires a 4.5:1 ratio. Large text (over 18pt) and meaningful UI components (like icons and input borders) require a 3:1 ratio.
The 'AAA' Standard
This is the strictest level of accessibility, generally required for specialized software or government services. It demands a 7:1 ratio for normal text and a 4.5:1 ratio for large text. Hitting AAA guarantees maximum readability.
Frequently Asked Questions
Color Contrast Checker: Free Online Tool
WCAG accessibility compliance isn't optional — it's the law in many jurisdictions, and it's just good practice. One of the most common accessibility failures is insufficient color contrast between text and its background. Our Color Contrast Checker lets you pick any foreground and background color combination and instantly tells you whether it meets WCAG 2.1 AA and AAA standards.
Enter a foreground color and background color using the color picker, hex input, or RGB values. The tool instantly calculates the contrast ratio using the WCAG luminosity formula and shows you whether that combination passes AA (4.5:1 for normal text, 3:1 for large text) or AAA (7:1 and 4.5:1) thresholds. A live preview shows your colors side by side.
Common uses include checking button text contrast against button backgrounds before shipping UI, ensuring your website meets WCAG accessibility requirements for public sector clients, auditing an existing design for contrast issues, choosing accessible brand colors for a new website, and testing hover and focus states for accessibility compliance.
Many contrast checkers only show you the ratio number without explaining what it means. Ours gives you plain-English pass/fail results for AA and AAA on both normal and large text — so a designer, developer, or project manager can instantly understand whether a color combination is accessible. Free, unlimited, no signup required.
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