WCAG Contrast Checker
Calculate the contrast ratio between a foreground and a background color using the official WCAG 2.1 luminance formula. The tool reports the ratio (e.g. "4.52:1") and pass/fail status for all four conformance levels: AA Normal (≥4.5:1), AA Large (≥3:1), AAA Normal (≥7:1), and AAA Large (≥4.5:1). Use this to verify body text, headings, button labels, and link colors meet accessibility minimums. Algorithm: linearize each sRGB channel via the gamma curve, weight as 0.2126·R + 0.7152·G + 0.0722·B for relative luminance, then compute (Llight + 0.05) / (Ldark + 0.05). All math runs in your browser.
Privacy
Runs entirely in your browser — nothing is sent to any server.
Cost
Free. No sign-up, no watermark.
Type
Audit
Related tools
Tools that work with the same formats — most users open one of these next.
Color Converter
Convert any color (hex, rgb, hsl, hsv, named) to every common format at once — runs locally in your browser.
Complementary Color Generator
Find the complementary (opposite) color for any hex / rgb / hsl input — instant, free, no upload.
Triadic Colors Generator
Generate a balanced 3-color triadic palette from any base color — runs locally, free.
Analogous Colors Generator
Generate an analogous 3-color palette (±30° hue) from any base color — instant, local.
Shade & Tint Generator
Generate N evenly-spaced shades (darker) and tints (lighter) of any base color — runs locally.
Random Color Generator
Generate N cryptographically-random colors with optional pastel / vibrant / dark / light constraints.
Frequently asked
Is WCAG Contrast Checker free to use?
Yes. WCAG Contrast Checker is completely free with no sign-up, no watermark, and no usage limits. Toolsly does not charge for any of its tools.
Do my files and data stay private?
Yes — WCAG Contrast Checker runs entirely in your browser using your device's CPU. Files and text are never uploaded to our servers, so your data stays private.
How does WCAG Contrast Checker work?
Open WCAG Contrast Checker, paste or fill in the input fields, and the result updates instantly. Everything runs in your browser — no upload, no waiting.
Which browsers does WCAG Contrast Checker support?
Any modern browser works — Chrome, Firefox, Safari, and Edge on desktop and mobile. WCAG Contrast Checker uses standard web APIs and does not require any plugin, extension, or sign-up.