Where RGB values come from
- Photoshop and GIMP: the colour picker shows R, G and B from 0 to 255. Photoshop also shows the HEX, but other apps don’t.
- Office apps: Word, PowerPoint and Excel custom colour dialogs use RGB.
- Code and plugins: some tools give colour channels as decimals between 0 and 1. Multiply each by 255 and round first:
0.25, 0.5, 0.75becomes64, 128, 191.
Paste the values in any common shape: rgb(64, 128, 191), 64 128 191 or 64,128,191. Values above 255 are capped at 255.
How the conversion works
Each channel is written as a two-digit base-16 number. Divide by 16: the whole part is the first digit and the remainder the second, with 10 to 15 written as A to F. For 191: 191 ÷ 16 = 11 remainder 15, which is BF. Do the same for 64 (40) and 128 (80), and the colour is #4080BF.
Questions
What if I have an alpha value as well?
The converter ignores a fourth value. Keep opacity separate in CSS, for example rgb(13 148 136 / 0.5), or add it as two more HEX digits yourself.
Where do I find the RGB of a colour in an image?
Upload the image to the colour picker and click the pixel; it shows RGB and HEX together.