Representative example
This example reflects the implemented transformation or analysis.
Input
#1F2937 on #FFFFFFOutput
Contrast ratio with pass or fail results for normal AA/AAA and large AA/AAA text.Color Contrast Checker
Calculate the contrast ratio between text and background colors and check WCAG AA and AAA thresholds for normal and large text.
- Free public tool
- No sign-up for this tool
- Processing clearly labeled
- Instant results
Content last reviewed
Contrast Ratio: 21.00:1
The quick brown fox jumps over the lazy dog.
This box previews your selected colors
Normal Text (14pt / 18px)
WCAG AAPASS
WCAG AAAPASS
Large Text (18pt / 24px)
WCAG AAPASS
WCAG AAAPASS
Quick Start
Add input
Enter a foreground color and a background color.
Choose options
Any color syntax accepted by the bundled Chroma color parser.
Review the result
Check the output or diagnostics, then use the available copy or download control where shown.
Examples
Input and output example 1
Input
#1F2937 on #FFFFFFOutput
Contrast ratio with pass or fail results for normal AA/AAA and large AA/AAA text.About the Color Contrast Checker
Color Contrast Checker addresses a focused developer workflow without requiring a command-line setup. Calculate the contrast ratio between text and background colors and check WCAG AA and AAA thresholds for normal and large text. Results update from the supplied input, making it useful for quick inspection, debugging, documentation, or test preparation.
In this tool, Color Contrast Checker: processing runs in the browser and the tool does not call an external conversion API. Input remains in page memory unless a confirmed browser feature such as file reading or local settings is described above.
How to Use Color Contrast Checker
Enter a foreground color and a background color.
Configure any color syntax accepted by the bundled chroma color parser.
Review the generated output, status, or validation message.
Copy or download the result when that control is available, and verify it in the destination where it will be used.
Key Features
Focused processing
Chroma validates both colors and calculates their luminance contrast ratio. The result is compared with 4.5, 7.0, 3.0, and 4.5 thresholds.
Input guidance
Color strings recognized by Chroma, including common hex and CSS color forms.
Immediate feedback
When to Use Color Contrast Checker
Application development
Use Color Contrast Checker to prepare or inspect values while implementing a feature.
Fault isolation
Run a small known input through Color Contrast Checker to distinguish formatting or syntax problems from surrounding application behavior.
Reviewable examples
Create a concise contrast ratio with pass or fail results for normal aa/aaa and large aa/aaa text. for tests, documentation, or code review.
How It Works
Processing flow
Chroma validates both colors and calculates their luminance contrast ratio. The result is compared with 4.5, 7.0, 3.0, and 4.5 thresholds.
Result handling
During processing, Color Contrast Checker: the result is rendered directly in the tool interface. Validation failures are displayed instead of being silently treated as successful output.
Supported Formats and Options
Formats
Accepted input
Color strings recognized by Chroma, including common hex and CSS color forms
Displayed output
Contrast ratio with pass or fail results for normal AA/AAA and large AA/AAA text.
Options
Available controls
Any color syntax accepted by the bundled Chroma color parser
Common Errors and Troubleshooting
Common errors
Invalid or incomplete input
Unexpected result
Confirm that the selected mode or syntax matches the source and that the input is complete.
Troubleshooting guide
Resolve the reported error
An unsupported or malformed color displays ?Invalid color format.? Reduce the input to the smallest failing case and confirm the selected controls.
Check an unexpected result
Review the documented limitation for Color Contrast Checker, then compare a known example with the same mode or syntax before processing a larger value.
Limitations and Important Notes
Contrast compliance alone does not assess font weight, interaction states, color blindness, or the accessibility of an entire interface.
Privacy and Data Processing
Color validation, contrast calculation, and preview rendering run locally with the bundled Chroma library. Entered colors are not sent to an analysis API.
Tips and Best Practices
Practical tips
Keep the original color strings recognized by chroma, including common hex and css color forms before using Color Contrast Checker.
Check the result against this limitation: Contrast compliance alone does not assess font weight, interaction states, color blindness, or the accessibility of an entire interface.
Best practices
Prepare a representative input
Start with a small value whose expected result you understand, then add the edge cases relevant to Color Contrast Checker. Preserve the original when the conversion or formatting is destructive.
Verify in context
Contrast compliance alone does not assess font weight, interaction states, color blindness, or the accessibility of an entire interface. Treat the displayed result as an intermediate artifact and test it in the runtime, parser, database, or document where it will actually be used.
Technical Details
Implementation note: Color Contrast Checker: chroma validates both colors and calculates their luminance contrast ratio. The result is compared with 4.5, 7.0, 3.0, and 4.5 thresholds.
Who Is This For?
Developers, QA engineers, technical writers, analysts, and students who need calculate the contrast ratio between text and background colors and check WCAG AA and AAA thresholds for normal and large text.
Frequently Asked Questions
Does Color Contrast Checker send input to an API?
No external processing API is used by this tool; its implemented operation runs in the browser.
What input is supported?
Color strings recognized by Chroma, including common hex and CSS color forms.
Why did the tool show an error?
What should I verify before using the result?
Contrast compliance alone does not assess font weight, interaction states, color blindness, or the accessibility of an entire interface.