APCA vs. WCAG: The Next Level of Accessible Color for Figma Designers
Discover why the new APCA contrast algorithm outperforms traditional WCAG ratios — and how AVA Palettes brings accessible color systems directly into your Figma workflow, free in beta.
TL;DR for busy designers
- WCAG 2.1 contrast math is outdated. It misses real-world readability, especially in dark mode.
- APCA is more accurate and future-proof. It matches how users actually see color and text.
- AVA Palettes (free in beta) brings APCA checks to Figma as part of the palette creation process, so you can design more accessible, readable products today.
What’s Wrong with WCAG Contrast Ratios?
For years, WCAG 2.1 contrast ratios have been the standard for accessible digital text — but they have big limitations. Designers often find:
- Combos that pass WCAG... but are tough to read.
- Combos that fail WCAG... but feel perfectly fine.
- WCAG mostly ignores text size, weight, and real viewing conditions.
- WCAG 2.1 contrast math doesn't account for modern display technologies
Fact: WCAG 2.1 uses a mathematical formula that doesn’t match how humans truly see contrast — especially in dark mode and on modern screens.
Meet APCA: Contrast That Matches Human Perception
APCA (Advanced Perceptual Contrast Algorithm) is a contrast model grounded in human visual perception research. Unlike WCAG 2.1, which is based on relative luminance ratios, APCA incorporates non-linear response curves that approximate the behavior of human cone cells (photoreceptors) and models contrast polarity (dark-on-light vs. light-on-dark) using perceptually uniform color spaces (such as LAB or OKLCH).
APCA was developed based on modern color appearance science, drawing on research such as the CIECAM02 color appearance model and studies of spatial vision. The algorithm applies a power-law transformation to luminance values, which more closely matches how the human eye perceives brightness differences, especially in the context of text on varying backgrounds.
According to recent work by Andrew Somers, and supported by studies on contrast perception in the Journal of Vision and Color Research & Application, human readability thresholds are not symmetrical: light-on-dark text and dark-on-light text have different perceptual requirements.
APCA is currently under consideration for WCAG 3.0. Unlike WCAG 2.1 ratios, APCA:
- Accounts for light-on-dark and dark-on-light (polarity)
- Adapts to text size, thickness, and weight
- Uses real visual science — not just math
- Gives nuanced, directional scores instead of blunt pass/fail
- Measures contrast in perceptually uniform color spaces
Result? Contrast measurements that better predict actual readability for real users, in real apps, on real devices.
WCAG vs. APCA: Side-by-Side Comparison
| Factor | WCAG 2.1 | APCA |
|---|---|---|
| Considers polarity | ❌ No | ✅ Yes |
| Adapts to text size/weight | ❌ Very Limited | ✅ Yes |
| Reflects human vision | ❌ Limited | ✅ Yes |
| Real-world readability | ❌ Often misses | ✅ Better matches |
| Dark mode accuracy | ❌ Problematic | ✅ Improved |
Example 1: WCAG Passes, APCA Fails
Example 2: WCAG Fails, APCA Passes with a warning
Example 3: WCAG Fails, APCA Passes
These differences are most noticeable in dark mode and with modern display technologies, where WCAG 2.1 contrast math often misrepresents actual readability.
Caveat: Both WCAG 2.1 and APCA primarily focus on luminance (brightness) contrast, not chromatic (color) contrast. While APCA is a significant advance, it does not fully model complex scenarios like glare, colored lighting, or very small text at extremely low contrast. Ongoing research continues to refine how accessibility guidelines map to real-world readability.
AVA Palettes: Accessible Color, Powered by APCA
AVA Palettes is a free Figma plugin (currently in beta!) that brings the next generation of accessible color science—APCA—directly into your design workflow. Instantly check APCA and WCAG contrast as you build or edit color palettes, and design more readable, inclusive products for everyone.
- Live APCA/WCAG feedback on every color ramp
- Perceptual, real-user contrast scores—not just math
- Build accessible, production-ready color systems in minutes
- Compare APCA and WCAG side-by-side as you design
- Reduce costly accessibility issues
- Design smarter, more inclusive products—today
The future of accessible color is here—start designing smarter with AVA Palettes and APCA.