RGB to CMYK Converter
Type a RGB value and get CMYK straight away. Everything runs in your browser — nothing is sent to a server.
How the conversion works
Normalise each channel to 0–1, take K = 1 − max(R,G,B), then C = (1−R−K)/(1−K) and so on. This is a plain conversion without an ICC profile, so follow your printer’s reference for real jobs.
RGB
RGB describes color the way a screen makes it: three lights added together, each from 0 to 255. All three at zero is black; all three at 255 is white. Because it mirrors the hardware it is exact and lossless, but it is hard to reason about — nudging a color slightly warmer means changing two or three numbers at once with no obvious direction.
CMYK
CMYK is for ink, not light. Instead of adding brightness it subtracts it: cyan, magenta and yellow filter the white of the paper, and a separate black plate keeps dark areas from turning muddy and soaking the sheet. The conversion below is the plain arithmetic one with no ICC profile, so treat the result as a starting point — your printer will shift it.
RGB to CMYK, step by step
Worked through with #FF6347. Every number comes from the same engine the converter above uses.
-
Scale each channel to 0–1
R 1 G 0.388 B 0.278 -
Pull out the black plate first
K = 1 − max(R,G,B) = 1 − 1 = 0% -
What is left for the other inks
C = (1−R−K)/(1−K) = 0% M = 61% Y = 72% -
Result
cmyk(0%, 61%, 72%, 0%)
RGB to CMYK examples
| Color | RGB | CMYK |
|---|---|---|
| Red | rgb(255, 0, 0) |
cmyk(0%, 100%, 100%, 0%) |
| Tomato | rgb(255, 99, 71) |
cmyk(0%, 61%, 72%, 0%) |
| Orange | rgb(255, 165, 0) |
cmyk(0%, 35%, 100%, 0%) |
| Gold | rgb(255, 215, 0) |
cmyk(0%, 16%, 100%, 0%) |
| Limegreen | rgb(50, 205, 50) |
cmyk(76%, 0%, 76%, 20%) |
| Teal | rgb(0, 128, 128) |
cmyk(100%, 0%, 0%, 50%) |
| Dodgerblue | rgb(30, 144, 255) |
cmyk(88%, 44%, 0%, 0%) |
| Royalblue | rgb(65, 105, 225) |
cmyk(71%, 53%, 0%, 12%) |
| Blueviolet | rgb(138, 43, 226) |
cmyk(39%, 81%, 0%, 11%) |
| Hotpink | rgb(255, 105, 180) |
cmyk(0%, 59%, 29%, 0%) |
Common questions
Do the four numbers have to add up to 100?
No. Each plate is independent — it is how much of that ink covers the area. Total coverage above roughly 300% is what printers warn about, because that much ink stops drying properly.
Why is pure black not 0/0/0/100 in my design tool?
Large black areas often use a rich black — a little cyan, magenta and yellow under the K — so they look deep instead of washed out. The plain formula never produces that; it is a print decision, not a math one.
Will the same RGB always give the same CMYK?
With this formula yes, but not across tools. Anything profile-aware — Photoshop, InDesign, a RIP — will give different numbers for the same RGB because it accounts for the output device.