WCAG 3 and APCA: what changed, and what to do today

The contrast ratio you've been calculating for a decade is being replaced. Here's how the new algorithm works and why it matters.

D
Devi Park
April 1, 2026 · 9 min read

(Mock post body.) WCAG 2.x's contrast ratio has been the legal standard since 2008, and it has well-documented blind spots. APCA — the proposed WCAG 3 algorithm — fixes most of them, but it's not yet a legal standard. Here's the practical version of what to do today...

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