Free Color Contrast Checker
Test foreground and background colors against WCAG 2.1 & 2.2 Level AA and AAA contrast ratio requirements. Instant results — no signup.
About WCAG Contrast Ratios
WCAG Success Criterion 1.4.3 (Contrast Minimum) requires a contrast ratio of at least 4.5:1 for normal text and 3:1 for large text at Level AA. Success Criterion 1.4.6 (Contrast Enhanced) raises the bar to 7:1 and 4.5:1 respectively at Level AAA. These thresholds are identical in WCAG 2.1 and WCAG 2.2, so a passing color pair satisfies both versions.
Large text is defined as 18pt or larger (approximately 24px) for regular weight, or 14pt or larger (approximately 18.66px) for bold weight.
Contrast is calculated using the relative luminance of both colors, following the W3C contrast ratio formula. Insufficient contrast is one of the most common accessibility issues — appearing on over 80% of scanned homepages.
Low contrast rarely travels alone: pages that fail it usually fail other checks too. Run the free accessibility checker to find every contrast failure on a live page — plus 50+ other WCAG 2.1 & 2.2 checks — or read our WCAG 2.1 & 2.2 overview for the full picture.
Contrast Checker FAQ
What is a color contrast ratio?
A contrast ratio measures the difference in perceived brightness (relative luminance) between two colors, on a scale from 1:1 (no contrast at all) to 21:1 (pure black on pure white). It is computed as (L1 + 0.05) / (L2 + 0.05), where L1 and L2 are the relative luminance of the lighter and darker color. WCAG uses this ratio to keep text readable for people with low vision or color vision deficiency.
What contrast ratio do I need to pass WCAG AA?
4.5:1 for normal text and 3:1 for large text (SC 1.4.3). Level AAA raises this to 7:1 and 4.5:1 (SC 1.4.6). User interface components and meaningful graphics also need at least 3:1 against adjacent colors (SC 1.4.11) — you can test those pairs in this tool too.
What counts as large text?
Text at least 18pt (about 24px) at regular weight, or at least 14pt (about 18.66px) at bold weight. Anything smaller is normal text and must meet the stricter 4.5:1 (AA) or 7:1 (AAA) thresholds.
Did WCAG 2.2 change the contrast requirements?
No. Success Criteria 1.4.3, 1.4.6 and 1.4.11 carried over from WCAG 2.1 to WCAG 2.2 unchanged, so a color pair that passes here passes both versions. See our WCAG 2.1 & 2.2 overview for what 2.2 did add.
How do I find contrast issues across a whole site?
This tool checks one color pair at a time. To find every low-contrast element on a real page — including text rendered over computed styles you did not pick by hand — run our free accessibility checker. It scans your site with axe-core and reports each contrast failure alongside 50+ other WCAG 2.1 & 2.2 checks, free with no signup.
Check Every Page on Your Site
This tool tests a single color pair. Scan your whole site for every contrast issue — plus 50+ more WCAG checks.