WCAG Color Contrast Ratio Checker & Accessibility Validator
Calculates precise relative luminance contrast ratios between foreground and background colors. Instantly evaluates WCAG 2.1 AA/AAA compliance for standard text, large headers, and graphical interface controls.
Evaluate color contrast compliance against WCAG 2.1 Level AA and AAA standards for normal text, large text, and UI components.
What is the WCAG Color Contrast Ratio Checker & Accessibility Validator?
This tool evaluates color contrast between text and background according to WCAG 2.1 standards, certifying compliance for accessibility levels AA and AAA.
Relative Luminance and Contrast Ratio Mathematics
The human eye perceives green light far more brightly than blue light. The W3C WCAG 2.1 specification defines relative luminance by linearizing gamma-compressed sRGB values ($V / 255 \le 0.04045$ vs exponential formula) and weighting channels: $0.2126$ Red, $0.7152$ Green, and $0.0722$ Blue. The contrast ratio ranges from 1:1 (no contrast) to 21:1 (pure black on pure white).
How to Use the WCAG Color Contrast Ratio Checker & Accessibility Validator
Input Text Color
Enter the HEX color code or use the color picker for your foreground text.
Input Background Color
Enter the HEX color code or pick your background canvas color.
Review Compliance Scores
Inspect the live ratio and check if it passes WCAG AA (minimum 4.5:1) and AAA (minimum 7:1).
Key Settings & Parameters
| Setting | What It Controls | Recommended Default |
|---|---|---|
| Text Size Standard | Normal text (<18pt) requires 4.5:1; Large text (>=18pt or >=14pt bold) requires 3.0:1. | Design for 4.5:1 across all body text |
Common Pitfalls to Avoid
-
• Using light gray text (#999999) on white background#999999 on white yields a contrast ratio of only 2.84:1, failing all WCAG standards. Darken to at least #595959 for AA compliance.
-
• Testing only primary buttons and ignoring placeholder textForm field placeholder text and helper copy must also satisfy contrast standards to remain accessible.
Pro Tips for Best Results
- If your brand color falls slightly short of 4.5:1, use it for bold headings (where 3.0:1 passes) and use a darker shade for body copy.
Local Processing Guarantee
Zero server communication. Color palettes remain local.
When to Use
- Auditing website design systems, button states, and brand color palettes for accessibility.
- Ensuring compliance with US Section 508, ADA Title III, and European EN 301 549 regulations.
- Checking mobile app UI elements for readability under direct outdoor sunlight.
- • Calculations assume solid color backgrounds. Gradient or photography backgrounds require testing the lowest-contrast point of the image.
Frequently Asked Questions
What is the WCAG Color Contrast Ratio Checker & Accessibility Validator?
This tool evaluates color contrast between text and background according to WCAG 2.1 standards, certifying compliance for accessibility levels AA and AAA.
Relative Luminance and Contrast Ratio Mathematics
The human eye perceives green light far more brightly than blue light. The W3C WCAG 2.1 specification defines relative luminance by linearizing gamma-compressed sRGB values ($V / 255 \le 0.04045$ vs exponential formula) and weighting channels: $0.2126$ Red, $0.7152$ Green, and $0.0722$ Blue. The contrast ratio ranges from 1:1 (no contrast) to 21:1 (pure black on pure white).
How to Use the WCAG Color Contrast Ratio Checker & Accessibility Validator
Input Text Color
Enter the HEX color code or use the color picker for your foreground text.
Input Background Color
Enter the HEX color code or pick your background canvas color.
Review Compliance Scores
Inspect the live ratio and check if it passes WCAG AA (minimum 4.5:1) and AAA (minimum 7:1).
Key Settings & Parameters
| Setting | What It Controls | Recommended Default |
|---|---|---|
| Text Size Standard | Normal text (<18pt) requires 4.5:1; Large text (>=18pt or >=14pt bold) requires 3.0:1. | Design for 4.5:1 across all body text |
Common Pitfalls to Avoid
-
• Using light gray text (#999999) on white background#999999 on white yields a contrast ratio of only 2.84:1, failing all WCAG standards. Darken to at least #595959 for AA compliance.
-
• Testing only primary buttons and ignoring placeholder textForm field placeholder text and helper copy must also satisfy contrast standards to remain accessible.
Pro Tips for Best Results
- If your brand color falls slightly short of 4.5:1, use it for bold headings (where 3.0:1 passes) and use a darker shade for body copy.
Local Processing Guarantee
Zero server communication. Color palettes remain local.
When to Use
- Auditing website design systems, button states, and brand color palettes for accessibility.
- Ensuring compliance with US Section 508, ADA Title III, and European EN 301 549 regulations.
- Checking mobile app UI elements for readability under direct outdoor sunlight.
- • Calculations assume solid color backgrounds. Gradient or photography backgrounds require testing the lowest-contrast point of the image.