The rgba() functional notation expresses a color according to its red, green, and blue components. An optional alpha component represents the color's transparency.

Note: CSS Colors Level 4 allows for space-separated in addition to comma-separated values.


rgba(255,255,255,.5) /* white with 50% opacity */
rgba(255 255 255 / 0.5); /* CSS Colors 4 space-separated values */


Functional notation: rgb[a](R, G, B[, A])

R (red), G (green), and B (blue) can be either <number>s or <percentage>s, where the number 255 corresponds to 100%. A (alpha) can be a <number> between 0 and 1, or a <percentage>, where the number 1 corresponds to 100% (full opacity).

Functional notation: rgb[a](R G B[ / A])

CSS Colors Level 4 adds support for space-separated values in the functional notation.

Browser compatibility

BCD tables only load in the browser

Space-separated values

BCD tables only load in the browser