Color Contrast Ratio Calculator
Free CalculatorCheck the WCAG contrast ratio between your text and background colours to make sure your design is readable and accessible.
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Runs in your browser β no numbers leave your device.
Your colours (RGB)
Red channel of your text colour.
Green channel of your text colour.
Blue channel of your text colour.
Red channel of your background colour.
Green channel of your background colour.
Blue channel of your background colour.
Contrast ratio
15.43 : 1
WCAG AA needs 4.5:1 (3:1 for large text); AAA needs 7:1.
How it works
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Why colour contrast matters
Contrast ratio measures how different your text colour is from its background, on a scale from 1:1 (identical) to 21:1 (black on white). The Web Content Accessibility Guidelines (WCAG) set minimum ratios so that people with low vision or colour deficiencies can read your content. Normal text needs at least 4.5:1 to pass AA, while large text (roughly 18pt, or 14pt bold) only needs 3:1.
The stricter AAA level asks for 7:1 for normal text and 4.5:1 for large text. This calculator applies the official WCAG relative-luminance formula to your RGB values, so you can check any text-and-background pair before shipping it β no eyeballing required.