Convert RGB to CMYK
Converting Red, Green, Blue (RGB) to Cyan, Magenta, Yellow, Key (black) (CMYK) is a precise, rule-based operation — both formats describe the same color with different numbers. Whether you are tuning a CSS custom property, matching a brand color across design tools, or preparing values for print, this page gives you an interactive converter, the exact RGB → CMYK method, a worked example, a quick-reference table and the details that matter (rounding, gamut and print caveats).
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How to convert RGB to CMYK
Take this real example — the color firebrick(#c2410c):
rgb(194, 65, 12) → cmyk(0%, 66.49%, 93.81%, 23.92%)
- Normalize R, G, B to 0–1.
- The key (black) plate is K = 1 − max(R, G, B).
- The ink plates are C = (1 − R − K)/(1 − K), and the same with G→M and B→Y. This is the standard screen conversion — real print separations depend on ICC profiles.
K = 1 − max(R,G,B); C = (1 − R − K)/(1 − K) (per channel, normalized 0–1)
RGB to CMYK conversion table
| Color | RGB | CMYK |
|---|---|---|
| White | rgb(255, 255, 255) | cmyk(0%, 0%, 0%, 0%) |
| Black | rgb(0, 0, 0) | cmyk(0%, 0%, 0%, 100%) |
| Red | rgb(255, 0, 0) | cmyk(0%, 100%, 100%, 0%) |
| Lime | rgb(0, 255, 0) | cmyk(100%, 0%, 100%, 0%) |
| Blue | rgb(0, 0, 255) | cmyk(100%, 100%, 0%, 0%) |
| VersatilBox accent | rgb(194, 65, 12) | cmyk(0%, 66.49%, 93.81%, 23.92%) |
| Tailwind blue-500 | rgb(59, 130, 246) | cmyk(76.02%, 47.15%, 0%, 3.53%) |
| Tailwind emerald-500 | rgb(16, 185, 129) | cmyk(91.35%, 0%, 30.27%, 27.45%) |
About these formats
RGB (Red, Green, Blue). RGB is the additive model screens use: every color is a mix of red, green and blue light from 0 to 255 per channel. It is the numeric base all on-screen conversions pass through.
CMYK (Cyan, Magenta, Yellow, Key (black)). CMYK is the subtractive model of print: inks layered on white paper. On-screen CMYK values are approximations — real print depends on ink profiles (ICC), not just numbers.
Frequently asked questions
How do I convert RGB to CMYK?
Normalize R, G, B to 0–1. The key (black) plate is K = 1 − max(R, G, B). The ink plates are C = (1 − R − K)/(1 − K), and the same with G→M and B→Y. This is the standard screen conversion — real print separations depend on ICC profiles. The converter above does it instantly, including the reverse direction.
What is RGB?
RGB — Red, Green, Blue — is the additive model screens use: every color is a mix of red, green and blue light from 0 to 255 per channel. It is the numeric base all on-screen conversions pass through.
What is CMYK used for?
CMYK (Cyan, Magenta, Yellow, Key (black)) is the subtractive model of print: inks layered on white paper. On-screen CMYK values are approximations — real print depends on ink profiles (ICC), not just numbers.
Is the RGB → CMYK conversion exact?
Numerically yes, colorimetrically no. The on-screen CMYK conversion is the standard ink approximation — an actual print run depends on the paper, ink and ICC profile, so treat the CMYK values as a starting point for prepress, not a proof.
Why does the CMYK value look different in other tools?
Small differences come from rounding (how many decimals are kept) and from out-of-gamut handling. This site follows the CSS Color 4 algorithms and shows OKLCH with 3 decimals, the same convention used by browsers and mainstream design tools.