How to use the RGB to CMYK Converter
Enter red, green and blue values from 0 to 255. You get CMYK as rounded percentages and as one-decimal values.
How the conversion works
Each RGB channel is scaled to 0 to 1. Black (K) is 1 minus the largest channel. Cyan, magenta and yellow are then worked out from what is left: C = (1 − R − K) ÷ (1 − K), and the same for M with green and Y with blue.
Screen colour versus print colour
This is the plain mathematical conversion with no colour profile. Real printing depends on paper, ink and press, and some bright screen colours cannot be printed at all. For brand work, ask your printer for their profile or use the CMYK values in your official brand guide.
The formula
K = 1 − max(R, G, B) ÷ 255; C, M, Y follow from K.
Examples
- rgb(59, 130, 246)
cmyk(76%, 47%, 0%, 4%) C 76.0 M 47.2 Y 0.0 K 3.5
- rgb(255, 0, 0)
cmyk(0%, 100%, 100%, 0%) C 0.0 M 100.0 Y 100.0 K 0.0
Common colours: RGB to CMYK
| RGB | CMYK |
|---|---|
| rgb(255, 0, 0) | cmyk(0%, 100%, 100%, 0%) |
| rgb(0, 255, 0) | cmyk(100%, 0%, 100%, 0%) |
| rgb(0, 0, 255) | cmyk(100%, 100%, 0%, 0%) |
| rgb(255, 255, 0) | cmyk(0%, 0%, 100%, 0%) |
| rgb(0, 255, 255) | cmyk(100%, 0%, 0%, 0%) |
| rgb(255, 0, 255) | cmyk(0%, 100%, 0%, 0%) |
| rgb(0, 0, 0) | cmyk(0%, 0%, 0%, 100%) |
| rgb(255, 255, 255) | cmyk(0%, 0%, 0%, 0%) |
| rgb(128, 128, 128) | cmyk(0%, 0%, 0%, 50%) |
| rgb(255, 165, 0) | cmyk(0%, 35%, 100%, 0%) |
Limitations and assumptions
Simple mathematical conversion. Printers use colour profiles, so printed results can differ.
Frequently asked questions
What is pure black in CMYK?
cmyk(0%, 0%, 0%, 100%) in this simple conversion. Printers often use a “rich black” that adds some cyan, magenta and yellow for a deeper tone.
Why does my printed colour look different?
Screens mix light and printers mix ink, so the range of colours differs. The numbers here are a starting point, not a colour-managed proof.
How do I convert CMYK to RGB?
Use the CMYK to RGB converter.