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RGB To CMYK Calculator

Work out rgb to cmyk instantly with clear inputs, formula shown and shareable results.

About RGB To CMYK Calculator

Black is one minus the largest normalised channel, and each subtractive ink is the shortfall of its complementary channel scaled by one minus black. This naive conversion ignores ink and paper profiles, so it gives the right structure but a print house will still need an ICC-managed conversion for accurate colour.

Formulas

Key

K = 1 - max(R, G, B), with channels normalised to 0-1

Inks

C = (1 - R - K) / (1 - K), and similarly for M and Y

Worked example

With the default values below, RGB To CMYK Calculator returns CMYK values of 76% C, 47.2% M, 0% Y, 3.5% K. Change any input above and every figure here is recalculated in your browser.

Inputs used

Redaccepts 0–255
59
Greenaccepts 0–255
130
Blueaccepts 0–255
246

Results

CMYK values
76% C, 47.2% M, 0% Y, 3.5% K
Cyan
76.02%
Magenta
47.15%
Black (key)
3.53%

Step by step

  1. 1Values used
  2. 2Key
  3. 3Inks
  4. 4CMYK values= 76% C, 47.2% M, 0% Y, 3.5% K
  5. 5Cyan= 76.02
  6. 6Magenta= 47.15
  7. 7Black (key)= 3.53

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the RGB To CMYK figure worked out?

K = 1 - max(R, G, B), with channels normalised to 0-1. Black is one minus the largest normalised channel, and each subtractive ink is the shortfall of its complementary channel scaled by one minus black.

Why does this matter?

This naive conversion ignores ink and paper profiles, so it gives the right structure but a print house will still need an ICC-managed conversion for accurate colour.

What do I need to enter?

Enter red, green, blue. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.

Related Calculators

RGB To CMYK Calculator – Calculate CMYK values & Cyan