Colourwise’s contrast tools implement the WCAG 2.2 formulas directly — every ratio and pass/ fail result is mathematically calculated, not estimated.
Contrast checker
Check the WCAG 2.2 contrast ratio between two colours.
WCAG guidance
Colourwise's contrast calculations follow WCAG 2.2 success criteria 1.4.3, 1.4.6 and 1.4.11.
Colour vision deficiency
Around 1 in 12 men and 1 in 200 women have some form of colour vision deficiency — simulate protanopia, deuteranopia, tritanopia and more.
Palette checker
Check every pairwise contrast ratio across a full palette at once, not just two colours.
Accessible pairings
Use the accessibility-aware group in What Goes With This Colour to find AA-compliant pairings.
HEKNO Ltd aims to make Colourwise usable by as many people as reasonably possible, targeting WCAG 2.2 Level AA as an internal design and testing baseline.
Colourwise implements keyboard navigation, visible focus states, semantic headings, screen-reader labels, sufficient contrast, zoom/reflow support and reduced-motion handling across its tools and content pages. Colour is never the only way information is communicated (e.g. contrast pass/fail also uses text and icons, not colour alone).
Known limitations: some data tables and evidence panels on deep colour-profile and history pages are dense; representative manual review, rather than a full page-by-page audit, has been completed to date.
For accessibility feedback or a reasonable adjustment, email hello@hekno.co.uk with the page, the problem, and your requested format or adjustment.