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Developer guide

Large Text Contrast Rules in WCAG

Use the correct contrast threshold when a heading or label may qualify as large text.

Short answer

Large text may use a lower WCAG contrast threshold: 3:1 for AA and 4.5:1 for AAA.

When this applies

In WCAG 2.x, large text generally means at least 24 CSS pixels (about 18 pt), or at least 18.66 CSS pixels bold (about 14 pt bold). If there is doubt, use the normal-text threshold.

Practical review steps

  1. Measure the rendered text, not the design-tool label.
  2. Confirm the bold weight is actually used in the browser.
  3. Use normal-text thresholds for small labels, helper text, and most controls.

Check the actual color pair

Use the free Contrast Check with the foreground and background colors from the real component. It provides an immediate AA and AAA ratio check in the current browser tab.

Source and limit

For the formal requirement, review W3C's WCAG contrast minimum guidance. A ratio result checks a color pair; it is not a complete accessibility audit.