Design for Everyone, Not Just Compliance
The Color Contrast Checker is a precision tool built for designers and developers who take accessibility seriously. Beyond meeting legal requirements like WCAG 2.1 and ADA, proper contrast ensures your content is readable for the 1 in 12 men and 1 in 200 women with color vision deficiency, as well as anyone reading a screen in bright sunlight.
The Technical Formula
Contrast ratio is calculated using Relative Luminance, which measures the perceived brightness of a color on a scale from 0 (black) to 1 (white).
// Relative Luminance (L)
L = 0.2126 * R + 0.7152 * G + 0.0722 * B
(where R, G, B are linearized sRGB values)
// Contrast Ratio
CR = (L1 + 0.05) / (L2 + 0.05)
(L1 = lighter, L2 = darker)
Developer Reference
Use CSS custom properties to manage accessible color pairings across your application. This approach makes global updates trivial.
/* Design System Tokens */
:root {
--text-primary: #1A1A1A;
--bg-primary: #FFFFFF;
/* Ratio: 16.1:1 (AAA Pass) */
}
WCAG 2.1 Conformance Levels
| Level | Text Type | Min Ratio | Current |
|---|---|---|---|
| AA | Normal Text (<18pt) | 4.5:1 | PASS |
| AA | Large Text (≥18pt) | 3:1 | PASS |
| AAA | Normal Text (<18pt) | 7:1 | PASS |
| AAA | Large Text (≥18pt) | 4.5:1 | PASS |
Chrome DevTools
In the Elements panel, click any color swatch in the Styles pane. The color picker shows the contrast ratio against the background and provides AA/AAA lines to snap to.
Firefox Accessibility
The dedicated Accessibility tab provides a full-page audit. Use "Check for Issues" → "Contrast" to identify all failing elements at once.
Figma & Design Tools
Plugins like Stark or A11y - Color Contrast Checker integrate directly into your design workflow, flagging issues before handoff.
Accessibility FAQ
Is Level AAA legally required?
In most jurisdictions, Level AA is the legal requirement (ADA, Section 508, EN 301 549). AAA is the gold standard and recommended for critical content like government services or healthcare.
Does contrast apply to icons and graphics?
WCAG 2.1 extends requirements to "non-text contrast" for UI components and graphical objects. The minimum ratio is 3:1 for all essential visual elements.
What about placeholders in inputs?
Placeholder text is notoriously low-contrast by default. Ensure your placeholders meet at least 4.5:1, or use alternative patterns like visible labels instead.
Can I fail for too much contrast?
Technically no, but pure black (#000) on pure white (#FFF) can cause eye strain for some users. A soft approach like #1A1A1A on #FAFAFA maintains high contrast with better readability.