WCAG 2.1 vs WCAG 3.0 — What Changes for Contrast

WCAG 3.0 is still a draft, but understanding the shifts in contrast methodology now will save rework later.

Last updated: May 2026

At a glance

Algorithm: Ratio (2.1) → APCA Lc (3.0)
Tiers: A/AA/AAA (2.1) → Bronze/Silver/Gold (3.0)
Scope: Per-page (2.1) → Outcome-based scoring (3.0)
Status: 2.1 — current; 3.0 — Working Draft

WCAG 3.0 (codename "Silver") is a fundamental rethink of accessibility conformance — moving from per-criterion pass/fail to outcome-based scoring across an entire experience. For contrast specifically, three changes matter most: APCA replaces the 2.1 ratio, rendered context replaces the strict large-text definition, and score bands replace AA/AAA tiers.

Algorithm change

WCAG 2.1 uses a luminance ratio (the 4.5:1 / 7:1 thresholds we all know). WCAG 3.0 adopts APCA, which produces a perceptual contrast score (Lc) on a roughly -108 to +106 scale. APCA accounts for polarity, font weight, and spatial frequency in ways the 2.1 formula cannot.

Conformance model change

WCAG 2.1 conformance is binary per criterion — you either pass 1.4.3 or you don’t. WCAG 3.0 introduces a scoring system where individual outcomes accumulate toward Bronze, Silver, or Gold conformance. A site with 95% of pages passing AA but a few problem pages can still earn Bronze — the all-or-nothing strictness of 2.1 is relaxed.

Whether this is good or bad is debated. Advocates say it incentivizes broader compliance; critics worry it weakens the floor.

Practical migration advice

Continue targeting WCAG 2.1 AA — it remains the legal standard everywhere. Add APCA Lc as a secondary metric in your design system audits to surface the cases where 2.1 marginally passes but the design feels low-contrast in practice.

When WCAG 3.0 reaches Recommendation status (years away), most well-designed AA palettes will already pass APCA. Tokens that need attention now: anything pairing a saturated mid-tone (mid-blue, mid-red) with another saturated color.

Frequently asked questions

When will WCAG 3.0 ship?

No firm date. The W3C Working Draft has been progressing since 2021 and the AG Working Group treats it as a multi-year effort. Realistic expectations are mid-to-late 2020s for Candidate Recommendation status, longer for legal adoption.

Will my AA site automatically pass WCAG 3.0?

Mostly yes for text, with edge cases on saturated mid-tones and dark mode. Non-text contrast may need review — WCAG 3.0 expands the scope of what counts as "informative" graphics.

Is APCA in the contrast checker above?

Yes. The Result card shows both the WCAG 2.1 ratio (with AA/AAA verdicts) and the APCA Lc score (with body/large/fluent guidelines). Use the 2.1 numbers for compliance today; treat APCA as a forward-looking check.