AA vs AAA thresholds?

Normal text: 4.5:1 (AA) / 7:1 (AAA). Large text (≥18pt, or ≥14pt bold): 3:1 (AA) / 4.5:1 (AAA).

How is the ratio computed?

sRGB channels are linearised then combined with BT.709 luminance weights. Ratio = (L1 + 0.05) / (L2 + 0.05). Matches the WCAG 2.2 spec verbatim.

Yes — the Swap button instantly inverts. Useful for testing dark-mode vs. light-mode pairings.

No — this is a two-color calculator. For image-based accessibility audits, use the Color Blindness Simulator alongside this tool.

Compute the relative contrast ratio between two colors and get AA / AAA verdicts

Prove your design meets its accessibility legal threshold with a number. No uploads, no accounts — it's a calculator.

Compute the WCAG 2.2 relative contrast ratio between two colors and see AA / AAA verdicts for normal and large text instantly.

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AA vs AAA thresholds?: Normal text: 4.5:1 (AA) / 7:1 (AAA). Large text (≥18pt, or ≥14pt bold): 3:1 (AA) / 4.5:1 (AAA).
How is the ratio computed?: sRGB channels are linearised then combined with BT.709 luminance weights. Ratio = (L1 + 0.05) / (L2 + 0.05). Matches the WCAG 2.2 spec verbatim.
Can I swap foreground / background?: Yes — the Swap button instantly inverts. Useful for testing dark-mode vs. light-mode pairings.
Can I upload an image?: No — this is a two-color calculator. For image-based accessibility audits, use the Color Blindness Simulator alongside this tool.