WCAG vs APCA: Which Contrast Standard Should You Use?
2026-09-14 · zhoujingkang · Founder
WCAG and APCA answer related but different questions. WCAG 2.1 gives the established ratio-based baseline used by audits and procurement; APCA models perceived contrast more closely for modern interfaces, especially dark mode. Use both when you are choosing production colors.
What WCAG measures
WCAG 2.1 expresses contrast as a ratio between foreground and background luminance. The familiar AA target is 4.5:1 for normal text and 3:1 for large text. It is predictable, widely documented and still the right compliance baseline.
What APCA adds
APCA reports an Lc value with polarity and perceptual weighting. It is useful for judging thin text, dark surfaces and combinations that pass a ratio but feel weak on screen. APCA is a design signal, not a replacement legal requirement.
A practical workflow
Run both checks in the ColorwayKit color contrast checker, fix failures without changing the brand hue, then test the resulting roles in a light and dark theme. For a complete system, send the primary color to the Brand Theme Engine.
Continue with a tool
References
FAQ
Should WCAG or APCA come first?
Use WCAG as the compliance baseline and APCA as a perceptual design check. Passing both gives stronger evidence that text will remain readable.
Can APCA replace WCAG?
No. APCA is complementary; WCAG 2.1 remains the established ratio-based standard for many audits.
Try it on your own brand color
Paste one hex into the Brand Theme Engine and get a full light & dark web theme — semantic tokens, contrast-checked, export-ready.
Open the Brand Theme Engine →