Free APCA Contrast Calculator
Calculate APCA (Lc) contrast — the modern perceptual contrast method behind WCAG 3.
APCA contrast
-108Lc
Excellent — suitable for any text, including thin and small fonts.
About the tool
Pick a text color and a background color to compute the APCA lightness contrast (Lc) value, along with plain-English guidance on which text sizes the pairing supports.
APCA models how the human eye actually perceives contrast, making it more reliable than the older WCAG 2 ratio — especially for dark backgrounds.
This free online tool is provided “as is” without any warranties, express or implied.
What is APCA?
APCA (Accessible Perceptual Contrast Algorithm) is the candidate contrast method for WCAG 3. Instead of a simple luminance ratio, it models how the human visual system perceives lightness, so its results line up much more closely with what people actually see on screen.
Its output is Lc (lightness contrast), a value from roughly 0 to 106. Higher numbers mean stronger perceived contrast: around 90 is excellent for any text, 75 is the minimum for body copy, and lower values are reserved for large or non-text elements.
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