Contrast Ratio Calculator
Check the contrast ratio between any two colours for accessibility
Embed Contrast Ratio Calculator ▾
Add this tool to your website or blog for free. Includes a small "Powered by ToolWard" bar. Pro users can remove branding.
<iframe src="https://toolward.com/tool/contrast-ratio-calculator?embed=1" width="100%" height="500" frameborder="0" style="border:1px solid #e2e8f0;border-radius:12px"></iframe>
Community Tips 0 ▾
No tips yet. Be the first to share!
Compare with similar tools ▾
| Tool Name | Rating | Reviews | AI | Category |
|---|---|---|---|---|
| Contrast Ratio Calculator Current | 4.5 | 1308 | - | Design & Creative |
| Box Shadow Generator | 4.9 | 3551 | - | Design & Creative |
| Border Radius Generator | 4.9 | 3744 | - | Design & Creative |
| Flexbox Visualiser | 4.3 | 3734 | - | Design & Creative |
| Spacing Scale Generator | 4.4 | 2584 | - | Design & Creative |
| SVG Optimiser | 5.0 | 2578 | - | Design & Creative |
About Contrast Ratio Calculator
Check Colour Contrast for Accessibility Compliance
The Contrast Ratio Calculator is a free tool that measures the contrast ratio between any two colours and tells you whether the combination meets WCAG accessibility standards. Enter a foreground colour and a background colour, and the tool instantly calculates the contrast ratio along with pass or fail ratings for each level of WCAG compliance. If you build websites, design interfaces, or create any digital content, this contrast ratio calculator is essential for ensuring your work is readable by everyone.
Understanding Contrast Ratios
Contrast ratio is a numerical measurement of the luminance difference between two colours, expressed as a ratio like 4.5:1 or 7:1. Higher ratios mean greater contrast and better readability. The Contrast Ratio Calculator computes this value using the WCAG 2.0 relative luminance formula, which accounts for how human eyes perceive different wavelengths of light. This is not a simple brightness comparison. It is a perceptually weighted calculation that accurately predicts whether text will be readable against a given background for users with various levels of visual ability.
WCAG Compliance Levels Explained
The Web Content Accessibility Guidelines define three levels of contrast compliance. Level AA requires a minimum contrast ratio of 4.5:1 for normal text and 3:1 for large text. Level AAA, the highest standard, requires 7:1 for normal text and 4.5:1 for large text. The contrast ratio calculator evaluates your colour combination against all of these thresholds simultaneously, so you can see at a glance whether your palette meets the minimum, exceeds it, or falls short. This information is critical for anyone legally required to meet accessibility standards or simply committed to inclusive design.
Why Accessibility Matters More Than Ever
Accessibility is not optional. In many jurisdictions, digital accessibility is a legal requirement under legislation like the ADA, the European Accessibility Act, and similar laws worldwide. Beyond legal compliance, accessible design is simply good design. Approximately 300 million people worldwide have some form of colour vision deficiency, and many more experience situational vision challenges due to screen glare, small text, or aging eyes. The Contrast Ratio Calculator helps you ensure that your content is readable by the widest possible audience.
A Designer Essential Tool
Professional designers use the contrast ratio calculator throughout their workflow. During palette selection, it validates that proposed colour combinations will work for text. During design review, it identifies potential accessibility failures before they reach development. During client presentations, it provides objective data to support colour recommendations. The tool transforms subjective discussions about whether colours look readable into objective, standards-based evaluations that leave no room for disagreement.
Developer-Friendly Output
The Contrast Ratio Calculator provides colour values in hex, RGB, and other formats that can be copied directly into CSS, design tools, or documentation. The numerical contrast ratio is useful for automated testing integration, and the WCAG pass/fail indicators map directly to the success criteria referenced in accessibility audits. Developers use this tool to validate colour choices during implementation, ensuring that the final product matches the accessible design intent without requiring a separate accessibility review for every colour decision.
Small Tool, Massive Impact
Colour contrast failures are the single most common accessibility issue on the web. Automated audits consistently find that over 80 percent of websites have at least one contrast violation. The contrast ratio calculator addresses this by making compliance checking effortless. It takes less than five seconds to test a colour combination, which means there is no excuse for shipping inaccessible colour choices. One small tool, used consistently, can prevent the most widespread category of accessibility failures in digital design.
Test your colours before your users struggle with them. The Contrast Ratio Calculator tells you instantly whether your design passes the accessibility bar.