Color Contrast Checker — WCAG AA/AAA & APCA
Use this color contrast checker to check any two colors against WCAG 2.2 or the emerging APCA method. Instant pass/fail, live preview, full threshold reference.
Large preview text
Normal-size preview text, the kind you'd actually read in a paragraph.
This preview always renders the exact colors entered above — the starting example is a real, common near-miss (mid-gray on white) that fails normal text but passes large text, so both a Pass and a Fail badge show below. Enter your own colors to check a different pairing.
How to use this checker
- Enter or pick a text color and a background color.
- Toggle WCAG 2.2 or APCA to switch scoring methods.
- Turn on Large text if you're checking a heading or other large/bold text — the pass/fail thresholds change accordingly in WCAG mode.
- Use Swap to flip text and background — useful for checking both light-on-dark and dark-on-light in one pass (and, in APCA mode, to see how the direction itself changes the score).
Understanding APCA
APCA (Accessible Perceptual Contrast Algorithm) was explored as a candidate contrast method for WCAG 3, developed to better predict how readable text actually looks to the human eye than a single fixed ratio can. It's worth being precise about where things actually stand: APCA was removed from the WCAG 3 working draft in 2023, and as of 2026 the W3C hasn't settled on a final contrast algorithm for WCAG 3 — APCA may or may not return in a later version. None of that changes what APCA measures or how useful it is today; it just means "the method behind WCAG 3" isn't a settled fact yet. A few things make it genuinely different from WCAG 2's formula, not just a different number on the same idea:
- It's a scaled Lightness Contrast (Lc) value, not a ratio. Scores range from roughly 0 to 106 for dark text on a light background, and 0 to -108 for light text on a dark background — the sign tells you the polarity, the magnitude tells you the strength.
- Order matters. Unlike WCAG's ratio, which is the same regardless of which color is text and which is background, swapping foreground and background in APCA changes the result. That's intentional: light-on-dark and dark-on-light don't read identically to the eye even at matched luminance difference.
- It accounts for font size and weight, not just color, in the fuller reading of the standard (this tool implements the base color-pair Lc calculation; pairing it with the widely-cited font-size/weight lookup table is the next step if you need a pass/fail against real text).
WCAG 2.2 AA remains the current legally-referenced accessibility standard, now also recognized as the international standard ISO/IEC 40500:2025. APCA was explored as a candidate method for WCAG 3 but was removed from the working draft in 2023, with no confirmed successor chosen as of 2026 — useful to check today as a more perceptually accurate alternative, but not yet a replacement for a WCAG 2.2 AA pass in a compliance context, and not a confirmed preview of what WCAG 3 will actually require.
| Lc (absolute value) | Guidance |
|---|---|
| 90+ | Preferred — fluent, highly readable text |
| 75+ | Good — standard body text |
| 60+ | Acceptable — large, bold headings |
| 45+ | Minimum — very large text or UI elements only |
| Below 45 | Insufficient — avoid using |
WCAG 2.2 contrast thresholds
| Level | Normal text | Large text | UI components / non-text |
|---|---|---|---|
| AA | 4.5:1 | 3:1 | 3:1 |
| AAA | 7:1 | 4.5:1 | — |
Related
A pairing that passes here in one theme is not guaranteed to pass in the other — a light-mode text/background combination and its dark-mode counterpart are two separate checks, not one. See how to choose dark-theme colors that actually pass contrast in both themes for the fuller framework.
Frequently Asked Questions
What's the difference between AA and AAA?
AA is the standard most accessibility guidelines and laws reference. AAA is a stricter, optional level for content where maximum readability matters most.
What counts as "large text" under WCAG?
18pt (24px) or larger at regular weight, or 14pt (18.66px) or larger at bold weight.
Does passing contrast mean my design is fully accessible?
No. WCAG Success Criterion 1.4.1 separately requires that color is never the only way information is conveyed — contrast passing is one requirement among several, not the whole picture.
Is WCAG 2.2 different from 2.1 for contrast?
No, the contrast success criteria and thresholds are unchanged between 2.1 and 2.2.
What is APCA and how is it different from WCAG?
See the "Understanding APCA" section above for the full explanation — in short, APCA is a perceptually-modeled score rather than a fixed ratio, and it's directional.
Should I use WCAG or APCA?
WCAG 2.2 AA is the current legal and compliance standard. APCA was explored as a candidate method for WCAG 3 but was removed from the working draft in 2023, with no confirmed successor chosen as of 2026 — still worth checking today as a more perceptually accurate method, but not a substitute for a WCAG 2.2 AA pass.
Sources
- WCAG 2.2 contrast thresholds and relative luminance formula (Success Criteria 1.4.3, 1.4.6, 1.4.11) — W3C Web Content Accessibility Guidelines 2.2
- APCA algorithm and constants (0.0.98G-4g) — Myndex APCA-W3 reference implementationThis page's implementation was checked against all 8 of Myndex's own published test vectors before launch, exact match.
- APCA's removal from the WCAG 3 working draft (2023) and current undetermined statusVerified against Adrian Roselli's WCAG 3 contrast status tracking (April 2026), a source that follows the W3C Accessibility Guidelines Working Group directly.
- WCAG 2.2's ISO/IEC 40500:2025 recognitionAnnounced by the W3C, October 2025.