WCAG calls text large from 24 px regular, or about 18.66 px bold, upward.

Does a pass guarantee readability?

No. The ratio ignores font weight, thin strokes, glare and individual vision. Treat it as a floor and test with real text.

Contrast Checker

Check text and background colours against WCAG 2.2 and get the nearest colours that pass.

Colours

Text (foreground)

Background

Picker edits

WCAG 2.2

Large text, 24px

Body text at 16px reads like this.

Button

Contrast ratio: 5.63:1

34.57

Check	AA	AAA
Normal text ≥ 4.5:1	Pass	Fail
Large text ≥ 3:1	Pass	Pass
UI and graphics ≥ 3:1	Pass	No AAA level

Nearest passing colours

Each keeps the hue and saturation and moves lightness only. Pick one to use it.

Text for AAAlready passes
Text for AAA#4e5567 · 7.07:1
Background for AAAlready passes
Background for AAANo lightness reaches it

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How it works

The ratio

The tool computes the contrast ratio between the two colours from their relative luminance, from 1:1 (identical) up to 21:1 (black on white), and compares it with the WCAG 2.2 thresholds.

ratio = (L_lighter + 0.05) ÷ (L_darker + 0.05)

What counts as a pass

Normal text needs 4.5:1 for AA and 7:1 for AAA. Large text needs 3:1 for AA and 4.5:1 for AAA. User-interface parts and graphics need 3:1.

When a pair fails, the tool offers the nearest colours that pass. Each keeps hue and saturation and moves only lightness, so the result stays recognisably your colour.

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