Color Contrast Checker
Developer toolNewCheck color contrast against WCAG AA and AAA.
This tool runs entirely in your browser. Your files never leave your device — nothing is uploaded.
Colors
Pick a text and background color. Everything runs in your browser — nothing is uploaded.
Result
17.40 : 1Contrast ratio
Normal text
AA: PassAAA: Pass
Large text (18.66px bold or 24px)
AA: PassAAA: Pass
Large sample text
The quick brown fox jumps over the lazy dog.
Frequently asked questions
What is a good WCAG contrast ratio?
WCAG requires a contrast ratio of at least 4.5:1 for normal body text and 3:1 for large text (around 24px, or 18.66px bold) to meet level AA. To reach the stricter AAA level you need 7:1 for normal text and 4.5:1 for large text. This tool shows the exact ratio and whether it passes each level.
How is the contrast ratio calculated?
Each color's sRGB channels are linearized and combined into a relative luminance value per the W3C formula. The ratio is then (lighter luminance + 0.05) divided by (darker luminance + 0.05), giving a number between 1:1 (no contrast) and 21:1 (black on white). The result is rounded to two decimal places.
Are my colors uploaded anywhere?
No. The entire calculation runs locally in your browser using JavaScript, so the colors you enter never leave your device or touch a server. There is no account, no tracking of your inputs, and nothing is stored — making it safe for confidential or unreleased brand work.