What contrast ratio do I need?

WCAG 2.1 requires 4.5:1 for normal text and 3:1 for large text (≥18.66px bold or ≥24px) at level AA. Level AAA raises this to 7:1 for normal and 4.5:1 for large text.

How is the contrast ratio calculated?

It uses the WCAG relative-luminance formula: the ratio is (L1 + 0.05) / (L2 + 0.05), where L1 and L2 are the lighter and darker colors' luminance. The result ranges from 1:1 to 21:1.

What counts as large text?

Text that is at least 24px, or 18.66px (14pt) when bold. Large text has a lower contrast requirement because it is easier to read.

No. Contrast is calculated locally in your browser.

Color contrast checker (WCAG)

Color tools

Check color contrast against WCAG AA and AAA. Enter text and background colors to see the contrast ratio and pass/fail for normal and large text. Free and private.

Check contrast against WCAG

Enter a text color and a background color to see the exact contrast ratio and whether it meets WCAG 2.1 accessibility levels for normal and large text.

The thresholds

AA — normal text: 4.5:1
AA — large text: 3:1
AAA — normal text: 7:1
AAA — large text: 4.5:1

Large text means ≥24px, or ≥18.66px when bold.

How to use it

Set the text (foreground) and background colors.
Read the contrast ratio and the pass/fail badges.
Use the live preview to judge readability at both text sizes.

FAQ

Operated by

Turnint AI Tools is a suite of free tools built and operated by unbounded pioneering inc, the company behind the Turnint AI agent platform.

Ryosuke SuzukiFounder & CEO

Founder & CEO of Unbounded Pioneering Inc., the company behind the Turnint AI agent platform, and an expert in machine learning and AI product development. He began his career in machine learning research at a university laboratory, then designed and built large-scale products as a software engineer at PLAID, Rakuten, and Recruit, while also driving new business development. Now specializing in generative AI and AI agents, he works across both engineering and business development, and is a named inventor on multiple granted patents in web technology.

Named inventor on granted patents JP6887648 & JP7480958 · Patent pending on Turnint AI technology

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