Color conversion

RGB to CMYK color conversion

Convert RGB (0–255) to CMYK. Approximate device-independent formulas, print notes, examples, and color chart. Runs locally in your browser. Try it free.

Instant result

Result

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Enter values to convert.

Inputs —

Mode —

Formula —

Formulas

Core equations used by this converter.

R'R' = R / 255

G'G' = G / 255

B'B' = B / 255

FormulaK = 1 − max(R', G', B')

CC = (1 − R' − K) / (1 − K)

isRGB-style 8-bit channels (0–255) unless noted. Calculation runs locally in your browser.

How to use

Choose RGB → CMYK or CMYK → RGB

Use the tabs in the converter to switch direction.

Enter RGB or CMYK values

RGB uses 0–255 channels; CMYK uses 0–100%.

Convert and read the result

Use Convert or let the result update automatically.

Example conversions

Common values with formula and result.

rgb(255, 0, 0) → CMYK

R'=1, G'=0, B'=0 → K = 0

cmyk(0, 1, 1, 0) or 0%, 100%, 100%, 0%

rgb(0, 0, 0) → CMYK

K = 1 → C = M = Y = 0

cmyk(0, 0, 0, 1) (100% black)

rgb(255, 255, 255) → CMYK

K = 0, C = M = Y = 0

cmyk(0, 0, 0, 0)

RGB to CMYK color conversion specification

Version 1.1.0 · Engine tested

Calculation status

Engine tested 3 published cases
Named expert review Not performed
Calculation version 1.1.0

Review policy

Definition: **RGB** — additive light (screens): red, green, blue **0–255**. **CMYK** — subtractive ink (print): **Cyan**, **Magenta**, **Yellow**, and **Key (black)**, usually **0–1** or **0–100%**.
What it calculates: Convert RGB (0–255) to CMYK. Approximate device-independent formulas, print notes, examples, and color chart.
Inputs: Values required by the selected conversion mode
Outputs: Converted result in the target unit or format
Formula: R' = R / 255 · G' = G / 255 · B' = B / 255
RGB to CMYK table: Color name RGB Hex CMYK (C,M,Y,K)
Black (0,0,0) #000000 (0, 0, 0, 1)
White (255,255,255) #FFFFFF (0, 0, 0, 0)
Red (255,0,0) #FF0000 (0, 1, 1, 0)
Green (0,255,0) #00FF00 (1, 0, 1, 0)
Blue (0,0,255) #0000FF (1, 1, 0, 0)
Yellow (255,255,0) #FFFF00 (0, 0, 1, 0)
Cyan (0,255,255) #00FFFF (1, 0, 0, 0)
Magenta (255,0,255) #FF00FF (0, 1, 0, 0)
Assumptions: Conversion runs locally in the browser; values are not uploaded.
Uses the formulas documented on this page.
Units: R'
G'
B'
Boundary conditions: Empty or invalid input yields no valid result.
Out-of-range values may be rejected by the tool runtime.
Example: rgb(255, 0, 0) → CMYK → cmyk(0, 1, 1, 0) or 0%, 100%, 100%, 0%
Validation cases: rgb(255, 0, 0) → CMYK → cmyk(0, 1, 1, 0) or 0%, 100%, 100%, 0%
rgb(0, 0, 0) → CMYK → cmyk(0, 0, 0, 1) (100% black)
rgb(255, 255, 255) → CMYK → cmyk(0, 0, 0, 0)
Sources: CalculatorX converter runtime
Standard unit / encoding definitions where applicable
Calculation version: 1.1.0

Color name	RGB	Hex	CMYK (C,M,Y,K)
Black	(0,0,0)	#000000	(0, 0, 0, 1)
White	(255,255,255)	#FFFFFF	(0, 0, 0, 0)
Red	(255,0,0)	#FF0000	(0, 1, 1, 0)
Green	(0,255,0)	#00FF00	(1, 0, 1, 0)
Blue	(0,0,255)	#0000FF	(1, 1, 0, 0)
Yellow	(255,255,0)	#FFFF00	(0, 0, 1, 0)
Cyan	(0,255,255)	#00FFFF	(1, 0, 0, 0)
Magenta	(255,0,255)	#FF00FF	(0, 1, 0, 0)

Background

Interpretation and common distinctions.

Use the converter tabs to switch direction when available. Results for RGB to CMYK color conversion update locally in your browser.

Frequently asked questions

Key distinctions behind the conversion.

How do you convert using RGB to CMYK color conversion?

Use R' = R / 255. Example: rgb(255, 0, 0) → CMYK → cmyk(0, 1, 1, 0) or 0%, 100%, 100%, 0%.

Can I switch direction?

Open the related reverse converter listed under Related tools.

Does this run online or locally?

Calculation runs locally in your browser. Values are not uploaded.

How precise are the results?

Results follow the formulas on this page. Round to the precision your use case needs.