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Alona Tool – Free Online Tools

Contrast Checker (WCAG AA & AAA)

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Calculate contrast ratios according to Web Content Accessibility Guidelines (WCAG 2.1). Check compliance for Normal Text, Large Text, and UI components across AA and AAA levels.

Browser-based: this tool works on your device and does not send your input to an Alona Tool server. See the Privacy Policy for details.
Fast Processing

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Example Usage & Test Cases

Dark text on light card
Input Scenario:
#0f172a on #f8fafc
Generated Result:
Contrast Ratio: 16.4:1 (Passes AAA Normal and Large)

How It Works

1

Calculates relative luminance (L1 and L2) using the standard W3C formula: (L1 + 0.05) / (L2 + 0.05).

Frequently Asked Questions

4.5:1 for normal text (under 18pt), and 3.0:1 for large text (18pt+ or 14pt bold) and graphical UI elements.

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Key Highlights:

  • Instant WCAG AA and AAA ratings
  • Live typography preview box
  • Invert colors button
  • Ratio calculation