Opacity Calculator

Any color at any opacity over any background, computed exactly: the resulting HEX, the rgba() you write in CSS, the solved alpha, and WCAG contrast of the result — plus a 0–100% ramp. Straight-alpha compositing, no guesswork.

opacity50%
#92B1F5rgba(37, 99, 235, 0.5)

Result contrast vs background: 2.14:1 WCAG AA normal ✗ AA large ✗

Opacity ramp (0–100% over #FFFFFF)
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Solved alpha

#2563EB at 100% opacity over #FFFFFF ≈ #000000. Reverse the math with the color mixer for arbitrary targets.

Opacity Calculator — HEX, rgba() and Contrast Over Any Background — Tintiva