Contrast Checker

Check whether text and background color combinations meet WCAG contrast thresholds for normal and large text.

Readable sample text

Result

Contrast ratio: 17.74:1

  • WCAG AA normal text: Pass
  • WCAG AA large text: Pass
  • WCAG AAA normal text: Pass
  • WCAG AAA large text: Pass

How to use this tool

Enter the required values in the labeled fields. Results update in your browser and are announced for assistive technologies. Use realistic measurements and verify important outcomes before acting on them.

Formula or logic

The calculator uses the WCAG relative luminance formula and contrast ratio (L1 + 0.05) / (L2 + 0.05).

Example calculation

Example: dark text #111827 on white has excellent contrast and passes AAA for normal text.

Frequently asked questions

What ratio passes AA normal text?

AA normal text requires at least 4.5:1 contrast.

What counts as large text?

WCAG large text is generally 18pt regular or 14pt bold and above.

Is the formula accurate?

Yes. It uses WCAG relative luminance and contrast ratio calculations.

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