RGB to CMYK Colour Converter
Estimate the Cyan, Magenta, Yellow and Black (CMYK) print percentages behind a screen RGB colour. Useful for artists and creators planning artwork that will eventually be printed.
Enter RGB Values
CMYK Result
C 40.3%, M 0%, Y 28.2%, K 51.4%
RGB: rgb(74, 124, 89)
Screen and Print Comparison
Screen Colour
Your RGB colour as shown on a screen.
Approximate CMYK Screen Preview
The rounded CMYK percentages converted back to screen colour — a rough guide only. Screens cannot truly display CMYK ink.
How to Use the RGB to CMYK Converter
- Enter a value from 0 to 255 for Red, Green and Blue, either by typing a number or dragging each slider.
- The estimated CMYK percentages update instantly below the inputs.
- Compare the Screen Colour swatch with the Approximate CMYK Screen Preview swatch to get a rough sense of how the colour may shift once converted for print.
- Select Copy CMYK or Copy RGB to copy the value you need.
- Select Random Colour to try a new combination, or Reset to return to the default colour.
How the RGB to CMYK Calculation Works
RGB describes colour as light, while CMYK describes colour as ink. Converting from one to the other uses the following mathematical steps:
- Divide each RGB channel by 255 to get a value between 0 and 1 (R′, G′, B′).
- K (black) = 1 minus the largest of R′, G′ and B′.
- If K equals 1, then C, M and Y are all 0.
- Otherwise: C = (1 − R′ − K) ÷ (1 − K), M = (1 − G′ − K) ÷ (1 − K), and Y = (1 − B′ − K) ÷ (1 − K).
- Convert C, M, Y and K to percentages.
Worked example: rgb(74, 124, 89) converts to approximately C 40.3%, M 0%, Y 28.2%, K 51.4%.
This is a general mathematical conversion, not a professional ICC colour-profile conversion. Actual printed results depend on your printer, ink set, paper and colour profile, and can differ from this estimate.
RGB versus CMYK for Artists
RGB is an additive colour model used by screens, where Red, Green and Blue light combine to create colour — combining all three at full strength produces white. CMYK is a subtractive model used in printing, where Cyan, Magenta, Yellow and Black ink absorb light from white paper to create colour. This is why a bright, glowing colour on your screen can look duller once printed — ink and paper simply cannot reproduce every colour a screen can display.
This matters for artists preparing printable art, packaging or instruction sheets: use this tool as an early planning estimate, and always check a test print before finalising an important print run. See the Paint Colour Mixer for guidance on physical paint mixing rather than commercial ink printing.
Examples
Frequently Asked Questions
What is CMYK?
CMYK stands for Cyan, Magenta, Yellow and Black — the four inks combined by most commercial printers to produce colour on paper.
Why is my screen colour different from RGB and CMYK?
RGB describes colour as light on a screen, while CMYK describes colour as ink on paper. The two use different physical processes, so a direct RGB-to-CMYK conversion is only an estimate.
Is this an exact conversion?
No. This tool applies a standard mathematical formula. A professional print run uses an ICC colour profile specific to the printer, ink and paper, which this tool does not replicate.
What does the Approximate CMYK Screen Preview show?
It shows the rounded CMYK percentages converted back into an RGB screen colour, as a rough visual guide to how the conversion may shift the colour. It cannot truly simulate ink on paper.
Why does the tool warn about some colours?
Very bright, highly saturated screen colours are often outside what CMYK ink can reproduce. The warning is a general indication, not a precise gamut test.
Can I use this to prepare a print-ready file?
This tool is for early planning and estimation. For an important print run, use your printer’s recommended colour profile and always request a test print.
Why is K sometimes 100% for dark colours?
When Red, Green and Blue are all very low, the formula assigns most of the darkness to the K (black) channel rather than mixing large amounts of C, M and Y.
Can pure white have any CMYK ink?
Mathematically, white converts to 0% for all four channels, since no ink is needed to represent white paper.
Does paper colour affect the result?
Yes, in real printing. This calculator assumes a neutral white background and does not account for coloured or textured paper stock.
Can I use this tool for fabric or ceramic printing?
It can offer a rough starting estimate, but specialised printing processes often have their own colour profiles and limitations beyond standard CMYK.
Is my colour data stored or sent anywhere?
No. All conversion happens directly in your browser. Nothing you enter is sent to a server or stored.
Can I use this tool on my phone?
Yes. The tool is designed to work on mobile, tablet and desktop screens.
Does this tool support Pantone colours?
No. Pantone is a proprietary, licensed colour matching system and is not included in this free tool.
Where can I find more colour tools?
Visit the Colour Tools hub for the full collection of converters, palette generators and colour learning tools.
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