About the RGB to CMYK Converter
Screens mix light (red, green, blue) while presses mix ink (cyan, magenta, yellow, key/black). Converting between them is a routine step before sending artwork to a printer. This converter applies the standard arithmetic formula and shows the result as percentages you can type straight into Illustrator, InDesign or a print order form.
How to use the RGB to CMYK Converter
- Enter a HEX code or RGB values, or use the colour picker.
- Read the cyan, magenta, yellow and key percentages.
- Compare the swatch against your design to confirm you have the right colour.
- Copy the CMYK string into your design software.
Why use this tool?
Standard formula
Uses the conversion built into design software: K from the brightest channel, then CMY relative to it.
Accepts any input
Three or six digit HEX, rgb() strings, or bare comma-separated numbers all work.
Honest about print
Tells you when a screen colour is outside what ink can reproduce instead of pretending the numbers are final.
Frequently asked questions
Why does my printed colour look duller?
Bright screen colours — vivid blues, neon greens, pure oranges — sit outside the CMYK gamut. Ink physically cannot reach them, so the press prints the nearest achievable colour.
Is this conversion the same as Photoshop's?
The arithmetic matches, but Photoshop also applies an ICC profile such as US Web Coated (SWOP) that accounts for paper and ink. For a commercial job, convert through the profile your printer specifies.
What does the K stand for?
Key. Black is the key plate the other colours are registered against, and the letter K avoids confusion with the B in RGB.