Convert screen colors with this RGB to CMYK converter
This RGB to CMYK converter takes the additive red, green, and blue values your monitor uses and turns them into the four-ink cyan, magenta, yellow, and key (black) percentages your printer needs. Drop in any RGB triplet (0–255) and you'll get clean CMYK output, a side-by-side swatch preview, and a gamut warning when the source color sits outside what process inks can physically reproduce on paper.
CMYK is a subtractive model used by commercial presses, where each percentage represents ink coverage on the plate. RGB, in contrast, is additive light — which is exactly why some neon screen colors simply cannot be printed. Screens emit light (RGB) while ink absorbs light (CMYK), and the RGB color space has a wider gamut, especially in bright greens, blues, and cyans.
The conversion formula
The converter normalizes your RGB inputs to a 0–1 range and applies the standard math:
R' = R / 255
G' = G / 255
B' = B / 255
K = 1 - max(R', G', B')
C = (1 - R' - K) / (1 - K)
M = (1 - G' - K) / (1 - K)
Y = (1 - B' - K) / (1 - K)Results are output as percentages from 0% to 100% for each channel, matching the input format used by Adobe Illustrator, InDesign, and most prepress workflows.
Why the gamut warning matters
Not all RGB colors can be accurately reproduced in CMYK due to the gamut limitations of ink on paper — bright neon colors, intense cyans, and vibrant purples often fall outside the CMYK gamut, and when this happens, colors are mapped to the closest reproducible CMYK color, which may appear significantly different. A built-in gamut indicator flags those risky colors before you send a file to press so you can adjust the design or choose a spot color instead. For deeper gamut analysis across modern color spaces, pair this with the OKLCH Gamut Checker.
Print workflow tips
- Design in CMYK from the start whenever the final deliverable is print.
- Use 100% K only for fine text; for solid black areas, use a rich black mix.
- Confirm the ICC profile your printer expects — SWOP, GRACoL, and Fogra39 all map gamut slightly differently.
- Always export a separate sRGB version for web and social media.
Need other formats in the same session? Convert in the opposite direction or fine-tune ink mixes with the HEX to CMYK Converter, blend process inks visually in the CMYK Color Mixer, or jump between every common color space with the all-in-one Color Converter.