Color Contrast Checker
Free, no signup. Compare foreground and background colors against WCAG 2.2 AA and AAA, get the closest practical hex alternatives that pass, or check a live URL's real rendered contrast.
Check a URL's rendered contrast
Loads the page in a metered headless browser and runs axe-core's color-contrast rule against the real computed styles — the resolved foreground, background, opacity, inherited color, and CSS variables after the cascade, not a static-HTML color guess. This is the same Browser-Rendering pipeline the AccessibilityWeb accessibility means designing sites so people with disabilities can use them, per the W3C's WCAG guidelines. It overlaps with SEO in specific, checkable ways — alt text, heading structure, descriptive link text, captions, and page speed all serve both audiences — but Google has said accessibility itself is not a ranking factor, and most WCAG success criteria (keyboard focus order, ARIA live regions, form labels) have no SEO effect at all. Tester uses, filtered to just contrast findings.
Checks run from our server; we fetch the URL you enter and don't keep the results. This launches a metered browser audit shared with the Accessibility Tester's rendering budget, so it is rate-limited per visitor and per target site. Anonymous run-level outcome counters may be used for aggregate research; URLs, domains, IPs, and identifiers are never included, and no statistic is released below 100 runs.
Runs entirely in your browser — nothing you paste is uploaded or stored. Anonymous run-level outcome counters may be used for aggregate research; URLs, domains, IPs, and identifiers are never included, and no statistic is released below 100 runs.
Palette audit
Paste CSS variables, token declarations, or a hex list. The matrix checks every color as text against every other color as a background.
Site passport Local context for this saved site
Local data
Saved targets, named lists, and recent check summaries remain only in this browser.
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Example
Example data — engine-verified result
#777777 foreground on #FFFFFF: 4.48:1
- Pass: AA large text and UI (3:1).
- Below: AA normal text and AAA large text (4.5:1), plus AAA normal text (7:1).
- Nearest AA normal-text alternative:
#767676, one step darker, at 4.54:1.
How it works
Paste mode calculates contrast from the WCAG relative-luminance formula, not by simply comparing RGB values. The suggestions preserve the foreground hue and saturation while walking its lightness toward the nearest passing color, then verify the rounded hex result. The URL mode above instead loads the page in a metered headless browser and reads each element's actual computed color and background after the CSS cascade resolves — the only way to catch contrast failures caused by inherited color, semi-transparent backgrounds, CSS variables, or the browser's default stylesheet, none of which a pasted color list can see.
Use the right rule
Normal-size text needs 4.5:1 for AA. Large text (at least 24px regular or 18.66px bold) and non-text UI indicators need 3:1. Color should never be the only way to communicate a state.
Frequently asked questions
What contrast ratio do I need?
WCAG AA requires 4.5:1 for normal text and 3:1 for large text and non-text UI components. AAA requires 7:1 for normal text and 4.5:1 for large text.
Does this prove my page is accessible?
No. It checks color pairs, not typography, focus states, images of text, or (in paste mode) real rendered backgrounds. Treat it as a design-time check and test the finished interface too.
Where does my palette go?
In paste mode it stays in the browser — paste CSS custom properties, Tailwind-style name/value tokens, or a loose list of hex colors. Only the URL mode sends anything to our server, and that is the public page address you enter, not a palette.
How is the URL mode different from pasting colors?
Pasted colors give you exact math on the pair you type. The URL mode loads the real page in a metered headless browser and reads each element's actual computed color and background after the CSS cascade, inheritance, opacity, and browser defaults are resolved — the only way to get a genuine contrast verdict for a live page, since a static-HTML color guess can be wrong.
Feature requests for Color Contrast Checker
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Common issues & how to fix them
- Errors Color pair fails WCAG AA for normal text Fix: Change the foreground or background until normal text reaches at least 4.5:1 contrast, then retest hover, focus, disabled, and visited states.
- Errors Color pair fails WCAG AA for large text Fix: Change the color pair until text at least 24px regular or 18.66px bold reaches 3:1 contrast.
- Warnings Color pair fails WCAG AAA for normal text Fix: Adjust the color pair until normal text reaches 7:1 contrast when AAA is the project requirement.
- Warnings Color pair fails WCAG AAA for large text Fix: Adjust the color pair until qualifying large text reaches 4.5:1 contrast when AAA is required.
- Warnings Color pair fails non-text contrast guidance Fix: Raise the contrast of essential icons, focus indicators, control boundaries, and graphical objects to at least 3:1 against adjacent colors.