Color Contrast Checker
Check color contrast ratio against WCAG accessibility standards. Test text and background colors for AA and AAA.
Almost before we knew it
We had left the ground — the quick brown fox jumps over the lazy dog.
About This Free Online Color Contrast Checker
Our free online color contrast checker measures the contrast ratio between a text color and a background color, then grades it against the WCAG 2.1 accessibility standards. Enter two hex colors and instantly see the ratio (from 1:1 to 21:1), whether it passes AA and AAA for normal and large text, and a live preview of the text on the background. Essential for designers and developers building accessible, readable websites. All calculations run in your browser.
Features of Our Color Contrast Checker
- WCAG contrast ratio from 1:1 to 21:1
- AA and AAA pass/fail for normal and large text
- Live text-on-background preview
- Uses official relative luminance formula
- Live results as you type
- 100% private — browser-only processing
How to Use the Color Contrast Checker
Using this tool is simple and requires no signup or registration. Follow these steps:
- Enter the text (foreground) color as a hex code.
- Enter the background color as a hex code.
- Read the contrast ratio and AA/AAA pass-fail badges.
- Adjust colors until you reach the level you need.
Frequently Asked Questions About Color Contrast Checker
What contrast ratio do I need?
WCAG AA requires at least 4.5:1 for normal text and 3:1 for large text (18pt or 14pt bold). WCAG AAA requires 7:1 for normal text and 4.5:1 for large text. Higher ratios mean more readable text.
How is contrast ratio calculated?
It compares the relative luminance of the two colors using the formula (L1 + 0.05) / (L2 + 0.05), where L1 is the lighter color. The result ranges from 1:1 (no contrast) to 21:1 (black on white).
What counts as large text?
WCAG defines large text as 18pt (about 24px) or larger, or 14pt (about 18.66px) bold or larger. Large text has slightly relaxed contrast requirements because it is easier to read.
Why Choose Text Toolbox?
Text Toolbox provides free, private, and instant online text tools. Unlike other text utility websites that require signup accounts or send your data to servers, all our tools process your text entirely in your browser. This means your content never leaves your device — we cannot see it, store it, or share it. Our tools are fast, lightweight, and work on any device with a modern web browser.