practice
APCA
APCA (Accessible Perceptual Contrast Algorithm) is a contrast-calculation method developed by Andrew Somers as a candidate replacement for WCAG's 2.0-era luminance contrast formula — designed to better reflect perceptual contrast across the visual range; currently being explored for inclusion in WCAG 3.0 but not yet adopted in normative WCAG.
About APCA
APCA produces a different numeric scale (target contrast 60 / 75 etc) and behaves differently from WCAG 2 contrast for dark mode and large text.
Where APCA appears in a AccessivePath audit
Our AI auditors test concepts like APCA as part of the WCAG 2.2 Level AA audit cycle — both via automated rule scanning and through screen-reader simulation and human pair review.
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