Aisha K.
Mar 12, 2026
Clean layout and the results update instantly. Exactly what I needed for a quick planning check.
Unit Converters
RGB to CMYK Converter
K = 1 − max(R,G,B); C,M,Y from (1 − channel − K) / (1 − K).
Naive uncalibrated RGB→CMYK: K = 1 − max(R,G,B); C = (1−R−K)/(1−K). Press CMYK needs an ICC profile. This is a first look, not a contract proof. Pure screen red will not print as a fire engine.
Screen RGB
Uncalibrated CMYK
C 0 / M 100 / Y 100 / K 0
A press wants an ICC profile.
Plain-English guide
Terms & how it works
Confused by a field? Read the short definitions here while you use the tool.
RGB
The “RGB” value used in this tool’s formula. Adjust it to see results update live.
How this calculator works
Naive uncalibrated RGB→CMYK: K = 1 − max(R,G,B); C = (1−R−K)/(1−K). Press CMYK needs an ICC profile. This is a first look, not a contract proof. Pure screen red will not print as a fire engine. K = 1 − max(R,G,B); C,M,Y from (1 − channel − K) / (1 − K). Example: rgb(255,0,0) → roughly 0, 100, 100, 0. Black rgb(0,0,0) → 0,0,0,100.
K = 1 − max(R,G,B); C,M,Y from (1 − channel − K) / (1 − K).
Example: rgb(255,0,0) → roughly 0, 100, 100, 0. Black rgb(0,0,0) → 0,0,0,100.
When to use this RGB to CMYK
Common use cases
- Naive uncalibrated RGB→CMYK: K = 1 − max(R,G,B); C = (1−R−K)/(1−K). Press CMYK needs an ICC profile. This is a first look, not a contract proof. Pure screen red will not print as a fire engine.
- Sanity-check with this case: rgb(255,0,0) → roughly 0, 100, 100, 0. Black rgb(0,0,0) → 0,0,0,100.
- The relationship is: K = 1 − max(R,G,B); C,M,Y from (1 − channel − K) / (1 − K).
Localized examples
- Unit Converters: the example on this page uses the same formula as the widget.
What you get
- Fields: RGB
- K = 1 − max(R,G,B); C,M,Y from (1 − channel − K) / (1 − K).
- Example on the page: rgb(255,0,0) → roughly 0, 100, 100, 0. Black rgb(0,0,0) → 0,0,0,100.
How to Convert RGB to CMYK Step-by-Step
- 1Enter RGB. Use the values you have, not a catalog average, unless that is all you know.
- 2K = 1 − max(R,G,B); C,M,Y from (1 − channel − K) / (1 − K).
- 3Worked case: rgb(255,0,0) → roughly 0, 100, 100, 0. Black rgb(0,0,0) → 0,0,0,100.
- 4Check which dictionary the other person is using — US or UK, decimal or 1,024 — then trust the number.
Governing formula
K = 1 − max(R,G,B); C,M,Y from (1 − channel − K) / (1 − K).
rgb(255,0,0) → roughly 0, 100, 100, 0. Black rgb(0,0,0) → 0,0,0,100.
Example: set RGB = 26, then read the result.
Variable definitions
- value
RGB
The “RGB” field. Default 26; typical range 0–255.
- The conversion (K = 1 − max(R,G,B); C,M,Y from (1 − channel − K) / (1 − K).) does not pick US vs UK gallons, SI vs binary megabytes, or Mach at altitude for you. Read the footnote on the page.
- Nothing here is uploaded for the calculation itself.
Frequently Asked Questions
Printers mix C/M/Y under K. This formula makes 100K for #000.
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Community
Reviews & Ratings
See what others think about this tool, then leave your own rating to help improve CalculioHub.
4.8
out of 5.0
4 reviews
Daniel R.
Feb 28, 2026
Very usable on mobile. Would love a save/export option later, but the math feels solid.
Priya S.
Feb 3, 2026
The FAQ section answered my questions before I even had to search. Smooth dark mode too.
Marcus L.
Jan 19, 2026
Simple inputs, clear outputs. This replaced three bookmarks I used to juggle.
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