WCAG3 Contrast as of April 2026
For years I have seen people, teams, products, organizations, and projects promoting APCA contrast as the WCAG3 color contrast algorithm. In many of those cases, those same actors have suggested dismissing the contrast algorithm in WCAG2.
This kind of problematic advice happened so often that I started filing issues with tool makers to remove APCA, as with this May 2024 Chromium issue.
In January 2025 I saw a post promoting that advice, which would create legal risk for anyone following it. You can see my original 2025 response on Mastodon and the same post on Bluesky, where the creator of APCA also weighed in. Read those to ensure you aren’t just taking my word for it.
Current Situation
Here is the most current (as of this writing) contrast ratio algorithm in WCAG3 with the salient bit highlighted:
- contrast ratio test Exploratory
meeting a sufficient level of contrast between two colors using the relationship of hue, saturation, and lightness values
Editor’s noteThe contrast algorithm used in WCAG 3 is yet to be determined.
APCA was marked for removal in early 2023:
Exploratory content that does not gain WG support to proceed to the next stage within 6 months is automatically removed in the WCAG 3 development process. We still hope the promising contrast work will continue to mature for potential later inclusion.
As with other WCAG3 ideas that did not get working group support, the working group pulled it from the July 2023 WCAG3 working draft. APCA was only ever exploratory, and the W3C’s July 2023 update explained removal of exploratory items. The APCA creator’s response to Michael Cooper’s comment acknowledged that APCA versions in the draft were all early versions that were very obsolete
(emphasis theirs).
I have no idea if APCA, whatever version, will come back to WCAG3.
What to Do?
You can still use APCA (whatever version). If you do, limit your risk by taking one of these approaches:
- Choose colors that also conform to WCAG2 contrast requirements; or
- If you pick colors that fail WCAG2 contrast requirements, document it and have a ready response should you receive a drive-by lawsuit from a bad actor using an automated checker to find a contrast violation (assuming your attorney lets you do this).
I am still not a (bird) lawyer.
In the meantime, WCAG3 is years away from being done, perhaps 2030 at the soonest. Any contrast algorithm it picks won’t be final until at least then. But if you like whatever is proposed and want to use it before 2030, then probably refer to my two approaches above.
3 Comments
Reply Lawsuit?? There’s a page on gov-uk about this, I had no idea there were legal requirements for accessibility before now.
In response to . Reply Without knowing where you are in the world, I suggest looking at Lainey Feingold’s Global Law and Policy page. It’s a reasonably current collection of digital accessibility laws around the world, which often reference a technical standard (typically WCAG).
Reply Hi Adrian, thanks for the update. A couple of clarifications for your readers.
I want to be completely clear: APCA is draft guidance we are actively testing and evaluating. This is not a final standard, and no one should be calling it “WCAG 3” — I’ve said so many times. The W3C a11y guidelines working group doesn’t conduct research—that is what we are doing at Inclusive Reading Technologies.
You’re right that nobody should drop WCAG 2 conformance based on a draft, no disagreement there. That said, the current algorithm and guidelines reflect years of work, independent validation, and peer-reviewed journal-published papers. The APC-RC guidelines all refer to well established peer reviewed research. In practice, colors that pass APCA for a given font size and weight greatly exceed WCAG 2’s minimums in the vast majority of cases. To be clear, nothing prevents APCA from being “backwards compatible” at all, that relates to the actual guidelines, not the math. The controversy, if you can call it that, are ranges of colors allowed or mandated by WCAG2 that can interfere with actual accessibility.
Nevertheless, for anyone who wants both, BridgePCA was designed for exactly that — it automatically passes WCAG 2, but extends improved accommodation using APCA, and several tools already support it.
— Andrew Somers,
Inclusive Reading Technologies
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