Contrast Checker: WCAG Contrast Ratio Calculator

Calculate WCAG contrast ratio between two colors with Contrast Checker. Get real-time results and grade your color contrast.

Colors

Foreground (Text)

Background

Preview & Results

Sample Text

The quick brown fox jumps over the lazy dog.

21.00

Contrast Ratio

AAA

WCAG Grade

AA (normal text, 4.5:1)

AA Large (3:1)

AAA (7:1)

Contrast Checker: WCAG Contrast Ratio Calculator

Quick Summary: Contrast Checker is a web tool that calculates the WCAG contrast ratio between two colors, providing real-time results and grade your color contrast.

What This Tool Does & Key Features

Contrast Checker is a web tool that helps you calculate the WCAG contrast ratio between two colors. It provides real-time results and grades your color contrast according to WCAG standards (AA, AA Large, AAA).

Step-by-Step How to Use Guide

Open the Contrast Checker tool.
Choose the foreground (text) color by clicking the color picker or typing the hex code in the text field.
Choose the background color by clicking the color picker or typing the hex code in the text field.
See the contrast ratio and grade displayed in real-time.

Underlying Formula / Technical Logic

The contrast ratio is calculated using the following formula:

Contrast Ratio = (L1 + 0.05) / (L2 + 0.05)

Where L1 and L2 are the relative luminance values of the foreground and background colors, respectively.

Practical Real-World Examples

Example 1: Foreground: #000000 (black), Background: #ffffff (white) Contrast Ratio: 21.00, Grade: AAA
Example 2: Foreground: #ffffff (white), Background: #000000 (black) Contrast Ratio: 21.00, Grade: AAA
Example 3: Foreground: #808080 (gray), Background: #ffffff (white) Contrast Ratio: 4.50, Grade: AA

Comparison or Decision Matrix / Checklist

Contrast Ratio	WCAG Grade
≥ 7.00	AAA
≥ 4.50	AA
≥ 3.00	AA Large

Common Mistakes & How to Avoid Them

Mistake: Using colors with low contrast ratios. How to Avoid: Always check the contrast ratio and grade before using colors in your designs.
Mistake: Ignoring WCAG guidelines for color contrast. How to Avoid: Use Contrast Checker to ensure your designs meet WCAG standards for accessibility.

Frequently Asked Questions

How does Contrast Checker calculate the contrast ratio?

Contrast Checker calculates the contrast ratio using the formula (L1 + 0.05) / (L2 + 0.05), where L1 and L2 are the relative luminance values of the foreground and background colors.

What is the difference between AA, AA Large, and AAA grades?

AA grade requires a contrast ratio of ≥ 4.50, AA Large requires a contrast ratio of ≥ 3.00, and AAA grade requires a contrast ratio of ≥ 7.00.

How can I use Contrast Checker to improve my website's accessibility?

Use Contrast Checker to calculate the contrast ratio between your text and background colors, and ensure it meets WCAG standards (AA, AA Large, AAA). This will help improve your website's accessibility for users with visual impairments.