Enter a hex color and adjust the alpha slider, and the tool converts it to the matching rgba() value live.
Split the hex into red, green and blue byte pairs, convert each to decimal, then append your alpha value.
Yes, 3-digit shorthand and 8-digit hex with alpha are both accepted and normalized.
Alpha runs from 0 (fully transparent) to 1 (fully opaque); values outside this range are clamped.