Free tool · nothing is uploaded
Free color contrast checker
Enter a text color and a background color. This page uses the WCAG 2 contrast formula and shows the ratio. Black on white is 21:1. The colors stay in your browser.
The colors stay in this browser.
How the ratio is calculated
- The ratio uses the WCAG 2 relative luminance formula. Black, #000000, on white, #FFFFFF, is 21:1. The same color on itself is 1:1.
- Normal text needs 4.5:1 for AA and 7:1 for AAA. Large text needs 3:1 for AA and 4.5:1 for AAA.
- Large text here means 18pt, about 24px, or 14pt bold, about 18.5px. This page does not measure a font on another site.
- #RGB and #RRGGBB are accepted. A 3-digit color is read by doubling each digit, so #1C5 is #11CC55.
- Pass or fail uses the full ratio. A ratio that is not a short decimal is shown to 2 decimal places.
This reports the WCAG 2 contrast of the two colors you type. It does not check a live page, and it does not change search ranking.
Questions about this checker
What is the contrast of black on white?
Black, #000000, on white, #FFFFFF, is 21:1. The same color on itself is 1:1.
What ratios does this check?
Normal text needs 4.5:1 for AA and 7:1 for AAA. Large text needs 3:1 for AA and 4.5:1 for AAA. Large text here means 18pt, about 24px, or 14pt bold, about 18.5px.
Does a passing ratio change search ranking?
No. This reports the WCAG 2 contrast of the two colors you type. It does not check a live page, and it does not change search ranking.
Does this tool upload the colors?
No. The colors stay in the browser. Blogoose does not receive them.