HEX to CMYK

HEX to CMYK converts any web hex colour code into the four ink percentages used in print and graphic design: Cyan (C), Magenta (M), Yellow (Y) and Black (K). Enter any valid hex value and the result updates instantly in your browser — nothing is sent to a server.

What is CMYK?

CMYK is a subtractive colour model used in colour printing. Unlike RGB, which adds light to produce colours on screens, CMYK works by layering inks that each absorb (subtract) certain wavelengths of light. A professional printer mixes these four ink channels to reproduce nearly any colour on paper.

• Cyan absorbs red light
• Magenta absorbs green light
• Yellow absorbs blue light
• Key (Black) adds depth and sharpness; using a separate black ink is more economical than mixing C, M and Y to approximate black

How the conversion works

Given a hex colour such as #3b82f6:

1. The hex is split into three 8-bit values: R = 59, G = 130, B = 246
2. Each channel is normalised to the range 0–1
3. The Black key is calculated as K = 1 − max(R′, G′, B′)
4. The three ink channels follow as C = (1 − R′ − K) / (1 − K), and similarly for M and Y
5. Each result is multiplied by 100 and rounded to the nearest integer percentage

When would you use this tool?

You have a brand colour defined in HEX for web use and need to hand off exact CMYK values to a print vendor. Or you are building a design system that must look consistent across both digital and physical output. Converting from HEX gives you a solid starting point — bear in mind that professional print workflows may apply ICC colour profiles and soft-proofing on top of these raw values.

Limitations

The conversion is a mathematical approximation based on the sRGB colour space. Physical ink and paper introduce variables such as ink gain, substrate colour and metamerism that can cause the printed result to differ visually from the on-screen swatch. For critical print work always request a physical proof from your printer.