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Contrast Checker
Two colours, five verdicts, no rounding favours. This is the classic WCAG contrast checker, kept honest: the verdict compares the unrounded ratio with the threshold, so a pair can display 4.50 and still fail — and the seeded pair below fails by nine thousandths, on purpose.
The thresholds: AA normal text 4.5:1 · AA large text 3:1 · AAA normal 7:1 · AAA large 4.5:1 · non-text and UI 3:1 against the adjacent colour. Large text means 24px or more, or 18.66px or more at bold weight — nothing else, however big it looks.
The two colours
One pair is a parity check, not a palette
This page exists because sometimes the question really is just two colours. But notice what it does with the answer: every result offers the pair's place in the whole-palette matrix and a route into the generator, because in a real interface this text colour also sits on a surface, beside a border, inside a dark theme. The checker shares the generator's measurement exactly — the same code path, tested against the same hand-computed vectors published on the methodology page — so a verdict here can never disagree with a verdict there.
Contrast checker questions
Does this checker use WCAG 2.1 or 2.2?
The verdicts are WCAG 2.1 criteria 1.4.3, 1.4.6 and 1.4.11. WCAG 2.2 did not change the contrast thresholds — 4.5:1 for normal text at AA, 3:1 for large text, 7:1 at AAA, 3:1 for non-text — so a pair graded here is graded identically under 2.2. The numbers are shown unrounded for the verdict and at two decimals for display; 4.496170 displays as 4.50 and fails, as the standard requires.
Why is the seeded pair failing?
The checker opens with #647A87 on white — a respectable-looking slate that measures 4.491467: just under the 4.5 line for normal text, while passing large text and non-text at 3:1. It is the most instructive failure there is: a colour most people would ship, failed by nine thousandths. Use the repair button and watch it cross the line by moving lightness only.
What is the APCA number under the verdicts?
A second opinion, labelled as such. APCA is a draft contrast method being developed for a future WCAG 3; it has no normative status today, and no verdict on this page is decided by it. It is shown because designers ask about it — the guide on APCA vs WCAG explains where the two methods disagree and why WCAG 2.1 is the one that decides compliance questions now.
One pair passes. Is my design accessible?
Not on that evidence alone. A passing pair is one pairing, in one state, on one ground. Design systems fail in the combinations: muted text on the tinted surface, the focus ring against the card, the dark theme nobody re-checked. That is why this page routes every result into the matrix and the generator — the pair is the start of the audit, not the audit.