Free tool
WCAG color contrast checker
Pick any two colors. We compute the WCAG luminance contrast ratio and tell you whether the pair passes AA and AAA for normal and large text. No signup, no upload.
Answer
WCAG 2.1 SC 1.4.3 (Contrast Minimum, AA) requires text to have a luminance contrast ratio of at least 4.5:1 against its background, with a relaxed 3:1 for large text (≥18pt or ≥14pt bold). WCAG 2.1 SC 1.4.6 (Contrast Enhanced, AAA) raises the bar to 7:1 for normal text and 4.5:1 for large text. The ratio is computed from the WCAG luminance formula on each sRGB channel — not hue or saturation. A failing pair on a Shopify storefront is the most common WCAG issue in 2026 (81% of homepage scans per WebAIM 2024). Use the tool below to check any color pair against both thresholds, or scan discoverable Shopify storefront pages for automated contrast issues.
Sample text — body copy
This is what your color pair looks like at normal weight and size.
Sample text — large heading
AA — Normal text
Needs 4.5:1
AA — Large text
Needs 3:1
AAA — Normal text
Needs 7:1
AAA — Large text
Needs 4.5:1
How this works
We use the WCAG 2.1 luminance formula. Each sRGB channel is converted to a linear value, combined with weights (R: 0.2126, G: 0.7152, B: 0.0722), and the ratio of the lighter to darker luminance plus 0.05 gives the final contrast ratio.
Pass thresholds: 4.5:1 for AA normal, 3:1 for AA large, 7:1 for AAA normal, 4.5:1 for AAA large. "Large" means at least 18pt or 14pt bold.
Find contrast failures across your Shopify storefront
The free public scanner checks up to 10 reachable pages, within safe time and page limits. The installed Free plan includes 3 supported rule-based fixes per rolling 30 days; Starter makes rule-based fixes unlimited.
Scan my Shopify store freeFAQ
What is the WCAG color contrast minimum?
WCAG 2.1 Success Criterion 1.4.3 (Contrast — Minimum) requires a luminance contrast ratio of at least 4.5:1 between body text and its background, with a relaxed 3:1 ratio for large text (at least 18pt or 14pt bold).
How is contrast ratio calculated?
Contrast is the ratio of the relative luminance of the lighter color to the darker color, both calculated using the WCAG luminance formula on each sRGB channel. The ratio runs from 1:1 (no contrast) up to 21:1 (black on white).
Does this tool replace a full accessibility scan?
No. Color contrast is only one part of accessibility. AccessComply checks supported automated rules on pages reached in the reported scan scope; many keyboard, assistive-technology, content, media, document, and task-flow requirements still need hands-on review.