RGB to CMYK Converter

Screens mix light (RGB) while printers lay down ink (CMYK: cyan, magenta, yellow and black). This converter gives the standard device-independent formula in both directions — RGB or HEX to CMYK percentages, and CMYK back to RGB and HEX — plus the total ink coverage that printers check. Use it for quick specs and mock-ups; for final print files, convert in your design software with your printer's ICC profile.

How to use this tool

1. Choose the direction.
2. For RGB → CMYK, type a HEX code, an rgb() value or a CSS color name.
3. For CMYK → RGB, enter the four percentages.
4. Copy the CMYK values or the HEX code; the swatch shows the screen color.

Formula

K = 1 − max(R′, G′, B′); C = (1 − R′ − K) ÷ (1 − K); M = (1 − G′ − K) ÷ (1 − K); Y = (1 − B′ − K) ÷ (1 − K). Reverse: R = 255 × (1 − C) × (1 − K), and likewise for G and B.

R′, G′ and B′ are the RGB values divided by 255. When K = 1 (pure black) C, M and Y are set to 0 to avoid dividing by zero.

Example

Dodger blue #1E90FF is rgb(30, 144, 255): R′ = 0.118, G′ = 0.565, B′ = 1. K = 1 − 1 = 0, so C = 1 − 0.118 = 88.2%, M = 1 − 0.565 = 43.5%, Y = 0% and K = 0%. Going back from C 0 M 44 Y 63 K 0 gives rgb(255, 143, 94), #FF8F5E.