The limits of numeric RGB-to-CMYK conversion

RGB describes combinations of light on a screen; CMYK describes ink channels used for printing. A simple formula can convert the numbers, but that does not predict a printer’s exact appearance.

This tool uses a mathematical conversion without a color profile. For example, #FF0000 is RGB 255,0,0 and becomes 0,100,100,0 in the simple CMYK model. Real ink and paper can look different.

For print approval, use the printer’s specified ICC profile and a proof. Converting between HEX and RGB in web development simply changes the notation of the same RGB channels.