SEO Report Tools

Webmaster Utilities · Runs in your browser · Free

Colour Contrast Checker

Check text and background colours against WCAG 2.2 contrast ratios.

What this tool does

Calculates the contrast ratio between two colours and reports pass or fail for AA and AAA levels for normal text, large text and interface components.

Who should use it

Designers and developers improving accessibility and readability.

How it works

Colours are converted to relative luminance using the WCAG formula, and ratio = (L1 + 0.05) ÷ (L2 + 0.05) with L1 the lighter luminance. Thresholds are 4.5 (AA normal), 3 (AA large and UI) and 7 (AAA normal).

How to use it

  1. Enter or paste text colour in the form.
  2. Adjust the options below the main box if you need to; the defaults suit most cases. Use "Load example" to see how input should look.
  3. Press the run button. Processing happens instantly in your browser.
  4. Review the result panel, then copy or download the output if the tool offers it. Use Reset to start over.

Practical example

White text on #767676 is exactly about 4.54:1, which passes AA for normal text.

Understanding the results

Large text means 18pt (24px) regular or 14pt (18.66px) bold and above.

Limitations

It does not consider font weight rendering, transparency or colour-blindness simulations.

Accuracy and report transparency

Results are computed in your browser from exactly what you enter. Deterministic steps (counting, parsing, encoding, validation) are verified by an automated test-suite with known answers. Where a method is a heuristic, the result panel says "estimated". No external data is used and nothing is invented.

Privacy

Your input never leaves your device for this tool. We count anonymous events (tool opened, run, copied) without storing what you typed. See the Privacy Policy.

Try these next

Mobile Readiness CheckerCheck static mobile signals: viewport tag, zoom blocking, fixed widths and media queries.Core Web Vitals Rating CheckerRate your LCP, INP and CLS values against Google's Good / Needs improvement / Poor thresholds.Image Alt Text CheckerFind images with missing, empty or overly long alt text and images without width and height attributes.

Frequently asked questions

Is contrast an SEO factor?

Not directly, but readable pages serve users better and accessibility is part of a good page experience.

Is my data sent to your server?

No. This tool runs entirely in your browser, so the text or files you enter stay on your device. We do record anonymous counts of how often each tool is opened or run (no input data) to see which tools are useful.

How accurate are the results?

Counting, parsing, encoding and validation steps are deterministic and covered by automated tests with known answers. Anything based on a heuristic is labelled "estimated" in the result panel.

Is this tool really free?

Yes. There is no account, limit or paid plan. The site is supported by advertising, which is disclosed on our Advertising Disclosure page.

References