Add the requested inputs
Use the labelled fields in the workspace above. If example values are provided, try them first or replace them with your own.
Digital & media · Free online tool
Colour contrast checker
Check foreground and background colours against WCAG contrast thresholds.
3 guest runs per rolling 24 hours10 with a free accountPrivate inputsMobile-friendly
Colour contrast checker workspace
Runs locally in your browser
Result
Contrast ratio—
Normal text AA—
Normal text AAA—
Large text AA—
Large text AAA—
Text luminance—
Background luminance—
Live colour preview
Readable text preview — Aa
Accessibility summary
Use it with confidence
How to use the colour contrast checker.
Calculate and review
Use the main action when needed. sRGB channels are linearised to relative luminance; contrast = (lighter + 0.05) ÷ (darker + 0.05).
Try a worked example
Test normal and large-text results, then swap the colours without re-entering them.
Check the assumptions
Passing contrast does not guarantee overall accessibility; also check size, weight, states and real content.
Helpful answers
Colour contrast checker FAQs.
Is the colour contrast checker free?
Yes. Guests receive 3 runs per rolling 24 hours, verified free accounts receive 10, and Premium subscribers receive unlimited normal use.
Does UtilHub upload or save my inputs?
No. This tool runs in your browser and UtilHub does not receive or store the values you enter. Your browser or device may still retain normal local history or form data.
How does this colour contrast checker work?
sRGB channels are linearised to relative luminance; contrast = (lighter + 0.05) ÷ (darker + 0.05).
What should I check before using the result?
Passing contrast does not guarantee overall accessibility; also check size, weight, states and real content.