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Color Contrast Checker

Calculates relative luminance and contrast ratio for foreground and background HEX colors, then reports AA and AAA thresholds for normal and large text separately. It does not replace testing the real interface.

✓ Free✓ No account✓ In-browser
QUICK ANSWER

What does this tool do?

Compare two colors against WCAG contrast ratios and text thresholds. Color Contrast Checker limitation: Keep the source copy and verify output interoperability in the target application.

Input
For Color Contrast Checker, provide supported color, CSS, SVG, image, or dimension values. The requested outcome is to compare two colors against WCAG contrast ratios and text thresholds.
Output
When Color Contrast Checker finishes, it returns a previewable visual value, dimension or format summary, and a copyable or downloadable result, organised around the goal to compare two colors against WCAG contrast ratios and text thresholds.
Method
Color Contrast Checker uses this disclosed method to compare two colors against WCAG contrast ratios and text thresholds: values are processed with browser APIs and disclosed conversion formulas while the source is preserved.
Verification
Before accepting a Color Contrast Checker result, complete visual comparison across light and dark backgrounds, viewport sizes, the target app, and the source; the evidence should support the goal to compare two colors against WCAG contrast ratios and text thresholds.
TOOL-SPECIFIC RUN PLANColor Contrast Checker: Input and result guideOpen the format, method, and acceptance check when needed

See exactly what Color Contrast Checker expects and returns

Color Contrast Checker uses the contract below to complete “Design-system color checks: local analysis with Color Contrast Checker” in particular. Confirm the shape with the example first; use real data only when the fields and expected result are clear.

  1. Use this shape

    1 · Prepare the input

    Color Contrast Checker — For Color Contrast Checker, provide supported color, CSS, SVG, image, or dimension values. The requested outcome is to compare two colors against WCAG contrast ratios and text thresholds.. Enter foreground and background HEX colors. Expected format for Color Contrast Checker: For Color Contrast Checker, provide supported color, CSS, SVG, image, or dimension values. The requested outcome is to compare two colors against WCAG contrast ratios and text thresholds..

  2. Method applied

    2 · Run the operation

    Color Contrast Checker — Color Contrast Checker uses this disclosed method to compare two colors against WCAG contrast ratios and text thresholds: values are processed with browser APIs and disclosed conversion formulas while the source is preserved. Calculate the ratio and thresholds. Color Contrast Checker applies this method: Color Contrast Checker uses this disclosed method to compare two colors against WCAG contrast ratios and text thresholds: values are processed with browser APIs and disclosed conversion formulas while the source is preserved.

  3. Expected output

    3 · Read the result

    Color Contrast Checker — When Color Contrast Checker finishes, it returns a previewable visual value, dimension or format summary, and a copyable or downloadable result, organised around the goal to compare two colors against WCAG contrast ratios and text thresholds.. Dark-mode readability: validating the Color Contrast Checker output

  4. Acceptance check

    4 · Accept or correct

    Color Contrast Checker — Before accepting a Color Contrast Checker result, complete visual comparison across light and dark backgrounds, viewport sizes, the target app, and the source; the evidence should support the goal to compare two colors against WCAG contrast ratios and text thresholds.. Test actual font size, weight, and state colors as well. Acceptance check for Color Contrast Checker: Before accepting a Color Contrast Checker result, complete visual comparison across light and dark backgrounds, viewport sizes, the target app, and the source; the evidence should support the goal to compare two colors against WCAG contrast ratios and text thresholds..

A tool-specific example path

1. Design-system color checks: local analysis with Color Contrast Checker → 2. Dark-mode readability: validating the Color Contrast Checker output → 3. CTA text accessibility: checking the limits of Color Contrast Checker

Tip: when an example-data button is available, run it first. Do not use the result in a live process unless it passes the acceptance check.

Operation statusReady
✓ Runs entirely in your browser
NEXT STEP

Process this result with another tool

The result stays briefly in this tab; continue directly to the next tool or build a longer visual flow.

01
Processing boundary

Input is processed only in the active browser tab's memory and is not sent to a ByteQuant server.

02
Persistent storage

Input and output are not stored. The optional usage counter keeps only tool identity and count, never content.

03
Verification

Output comes from disclosed rules or browser APIs and needs independent review before high-impact use.

APPLICATION AND DECISION GUIDE

Use Color Contrast Checker with the right input, acceptance check, and next step

✓ REVIEWED

Calculates relative luminance and contrast ratio for foreground and background HEX colors, then reports AA and AAA thresholds for normal and large text separately. It does not replace testing the real interface. The notes below help you do more than produce a result: they show how to test whether Color Contrast Checker fits the task and when to stop before a weak output travels further.

How does the tool actually work?

Color Contrast Checker uses this disclosed method to compare two colors against WCAG contrast ratios and text thresholds: values are processed with browser APIs and disclosed conversion formulas while the source is preserved. The target format is validated after conversion and lossy or browser-dependent behavior is disclosed. Keep the original copy for important files.

Input check before you begin

For Color Contrast Checker, provide supported color, CSS, SVG, image, or dimension values. The requested outcome is to compare two colors against WCAG contrast ratios and text thresholds. Confirm the shape first with a small example containing no personal data.

How should you interpret the output?

When Color Contrast Checker finishes, it returns a previewable visual value, dimension or format summary, and a copyable or downloadable result, organised around the goal to compare two colors against WCAG contrast ratios and text thresholds. — Before accepting a Color Contrast Checker result, complete visual comparison across light and dark backgrounds, viewport sizes, the target app, and the source; the evidence should support the goal to compare two colors against WCAG contrast ratios and text thresholds.

Three practical use cases

01

Design-system color checks: local analysis with Color Contrast Checker

Action: Start with a small synthetic fixture that represents this need. Expected input: For Color Contrast Checker, provide supported color, CSS, SVG, image, or dimension values. The requested outcome is to compare two colors against WCAG contrast ratios and text thresholds..

Acceptance signal: The fixture should reproduce “Design-system color checks: local analysis with Color Contrast Checker” without real personal data.

02

Dark-mode readability: validating the Color Contrast Checker output

Action: Keep that fixture unchanged and run the on-device method: Color Contrast Checker uses this disclosed method to compare two colors against WCAG contrast ratios and text thresholds: values are processed with browser APIs and disclosed conversion formulas while the source is preserved.

Acceptance signal: Identical input should return the same result, with no network or file action assumed beyond the disclosed method.

03

CTA text accessibility: checking the limits of Color Contrast Checker

Action: Retain the output record before moving it into the target workflow: When Color Contrast Checker finishes, it returns a previewable visual value, dimension or format summary, and a copyable or downloadable result, organised around the goal to compare two colors against WCAG contrast ratios and text thresholds..

Acceptance signal: Acceptance requires Before accepting a Color Contrast Checker result, complete visual comparison across light and dark backgrounds, viewport sizes, the target app, and the source; the evidence should support the goal to compare two colors against WCAG contrast ratios and text thresholds.; otherwise do not move the result forward.

Stop condition before using the result

Do not use the result for a decision beyond this boundary: Color Contrast Checker limitation: Keep the source copy and verify output interoperability in the target application.

Safe next step

Move the result to another tool or live process only after Before accepting a Color Contrast Checker result, complete visual comparison across light and dark backgrounds, viewport sizes, the target app, and the source; the evidence should support the goal to compare two colors against WCAG contrast ratios and text thresholds.. Keep this limit visible in the decision record: Color Contrast Checker limitation: Keep the source copy and verify output interoperability in the target application.

Latest content and method review:
HOW TO USE IT

A result in three steps

  1. 01

    Enter foreground and background HEX colors. Expected format for Color Contrast Checker: For Color Contrast Checker, provide supported color, CSS, SVG, image, or dimension values. The requested outcome is to compare two colors against WCAG contrast ratios and text thresholds..

  2. 02

    Calculate the ratio and thresholds. Color Contrast Checker applies this method: Color Contrast Checker uses this disclosed method to compare two colors against WCAG contrast ratios and text thresholds: values are processed with browser APIs and disclosed conversion formulas while the source is preserved.

  3. 03

    Test actual font size, weight, and state colors as well. Acceptance check for Color Contrast Checker: Before accepting a Color Contrast Checker result, complete visual comparison across light and dark backgrounds, viewport sizes, the target app, and the source; the evidence should support the goal to compare two colors against WCAG contrast ratios and text thresholds..

GOOD USE CASES

When is this tool useful?

  • ✓ Design-system color checks: local analysis with Color Contrast Checker
  • ✓ Dark-mode readability: validating the Color Contrast Checker output
  • ✓ CTA text accessibility: checking the limits of Color Contrast Checker
Tool-specific limitation

Color Contrast Checker limitation: Keep the source copy and verify output interoperability in the target application.

LEARN THE WORKFLOW

Guides for this tool

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ABOUT THIS TOOL

Frequently asked questions

What input does Color Contrast Checker accept?+

For Color Contrast Checker, provide supported color, CSS, SVG, image, or dimension values. The requested outcome is to compare two colors against WCAG contrast ratios and text thresholds. Enter foreground and background HEX colors. Expected format for Color Contrast Checker: For Color Contrast Checker, provide supported color, CSS, SVG, image, or dimension values. The requested outcome is to compare two colors against WCAG contrast ratios and text thresholds..

What does Color Contrast Checker return?+

When Color Contrast Checker finishes, it returns a previewable visual value, dimension or format summary, and a copyable or downloadable result, organised around the goal to compare two colors against WCAG contrast ratios and text thresholds. Color Contrast Checker uses this disclosed method to compare two colors against WCAG contrast ratios and text thresholds: values are processed with browser APIs and disclosed conversion formulas while the source is preserved.

How should I validate Color Contrast Checker output?+

For “Design-system color checks: local analysis with Color Contrast Checker”, first complete “Calculate the ratio and thresholds. Color Contrast Checker applies this method: Color Contrast Checker uses this disclosed method to compare two colors against WCAG contrast ratios and text thresholds: values are processed with browser APIs and disclosed conversion formulas while the source is preserved.”, then apply this check: “Test actual font size, weight, and state colors as well. Acceptance check for Color Contrast Checker: Before accepting a Color Contrast Checker result, complete visual comparison across light and dark backgrounds, viewport sizes, the target app, and the source; the evidence should support the goal to compare two colors against WCAG contrast ratios and text thresholds..”. Do not use a consequential result before a second test with boundary or malformed input.

Does this tool send or store input on a server?+

No. Processing runs in this browser tab and tool input is not persisted. Copying, downloading, or transferring happens only when you choose it.