TechTensteinBrowser-only accessibility check
Color contrast checker.
Compare foreground and background colors against common WCAG 2.2 thresholds. No color values are sent to TechTenstein.
Method and source
The calculator converts sRGB channel values to relative luminance and applies the WCAG contrast-ratio formula. Threshold labels are based on WCAG 2.2 Success Criterion 1.4.3 and Success Criterion 1.4.11. Always review the complete applicable standard and test the implemented interface.
WCAG 2.2 AA contrast thresholds
| What you are checking | Minimum ratio | Success criterion |
|---|---|---|
| Normal text | 4.5:1 | 1.4.3 Contrast (Minimum), AA |
| Large text | 3:1 | 1.4.3 Contrast (Minimum), AA |
| Meaningful interface components and graphical objects | 3:1, where the criterion applies | 1.4.11 Non-text Contrast, AA |
How the ratio is calculated
Each six-digit hex color is split into its red, green and blue sRGB channels. The calculator converts those channels to relative luminance and divides the lighter luminance plus 0.05 by the darker luminance plus 0.05. The calculation runs in your browser, so no color values are sent to TechTenstein.
Where contrast fits in a wider review
Contrast is one check, not full conformance. The accessibility quick review lists the keyboard, zoom, screen-reader, focus and task-based tests that still need people, and the free website audit tool checks landmarks, language, image alternatives, link names and form labels. For interface work with accessibility requirements built into the scope, see TechTenstein’s UI/UX design service.