When the Color Contrast Checker seems to misbehave, the cause is usually one of two things: something stopped the tool from running, or it ran but the result is not usable. This guide starts with the fastest checks, then walks through the common problems and exact fixes.
Quick Checks First
- Refresh the page - a stalled session is the most common cause of nothing happening.
- Confirm the input is not empty and actually contains what you meant to submit.
- Try the smallest possible input; if that works, the issue is size, not the tool.
- Turn off browser extensions that block scripts, then reload and test again.
- Update or switch browsers if the problem repeats across sessions.
Common Problems and How to Fix Them
The ratio failed AA
Darken the text or lighten the background - small value moves shift ratios quickly.
Large text passed but body text failed
Body copy needs 4.5:1 - design for the smallest text you actually ship.
Passing colours look bad together
Accessibility is a floor, not a style - keep adjusting hue and lightness until both hold.
It passed but users still complain
Contrast is not the only barrier - check font size, weight and line length too.
Dark mode fails where light passed
Test every mode separately; inversion changes ratios unpredictably.
I need the result for documentation
Record the exact ratio alongside the colour pair - auditors ask for numbers, not impressions.
When It Works but the Output Is Poor
If the tool runs fine but the result misses, the problem is almost always the brief, not the software:
- Checking only the default text colour
- Assuming brand colours will pass
- Validating one mode while shipping both
- Treating a pass as proof of good design
How to Stop It Happening Next Time
- Keep a saved prompt template for every task you repeat.
- Change one setting per generation so causes stay obvious.
- Run a two-minute sanity test with known input after any update.
- Note every failure and its fix; a short troubleshooting log pays for itself.
Still Stuck?
Reproduce the problem with the smallest possible input and note the exact steps that triggered it. A one-line description of what you did, what you expected and what happened is enough to get a precise answer from support or a colleague.
Frequently Asked Questions
What contrast ratio do I need?
WCAG AA requires 4.5:1 for normal text and 3:1 for large text; AAA raises normal text to 7:1.
What counts as large text?
Roughly 18pt regular or 14pt bold - the tool applies the official thresholds for you.
Does passing guarantee accessibility?
No - contrast is one requirement among many, but failing it is a definite barrier.
Are my colours uploaded?
No - all calculations run in your browser.
Related Guides
- How to Use Color Contrast Checker
- What Is a Color Contrast Checker and How Does It Work?
- Color Contrast Checker Examples: Real Scenarios and Results
- Color Contrast Checker for Designers and Front-end Developers
- Best Color Contrast Checker Alternatives Worth Trying
- Color Contrast Checker Tips and Best Practices
- Is Color Contrast Checker Safe? Free vs Paid
- More color tools and guides