Checking a brand colour for print
Convert your screen colour to CMYK to see roughly how much of each ink it needs before sending artwork to a printer.
RGB to CMYK
Convert an RGB colour to CMYK in your browser, the model print uses.
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Use RGB to CMYK
Converts rgb colour to cmyk in this tab, with nothing sent anywhere.
Runs entirely on your deviceThe conversion happens in this browser tab. Nothing you type is uploaded, logged or stored, which is worth knowing for anything you would not paste into a search box.
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Browse all general convertersAbout RGB to CMYK
Screens make colour by adding light - red, green and blue - while print makes it by subtracting light with ink: cyan, magenta, yellow and a key black. The two models are fundamentally different, which is why a colour that glows on a monitor can look flat on paper, and converting RGB to CMYK is the first step in preparing a screen colour for print. This gives you the four ink percentages using the standard arithmetic conversion, which is exactly the sort of estimate a designer uses to sanity-check a colour before committing to a print run. It is worth being honest that no formula-based conversion is colour-accurate for real printing, because that depends on the specific inks, paper and press - but as a working approximation and a starting point, it is genuinely useful.
Using RGB to CMYK
- The three RGB channels are read and normalised to a 0-to-1 range.
- The key (black) component is derived from the brightest channel - the more colour present, the less black is needed.
- The cyan, magenta and yellow components are calculated relative to that black level.
- All four are expressed as percentages, the way CMYK is written in design tools.
- Pure black short-circuits to 100% key with no other ink, avoiding a divide-by-zero.
Where rgb to cmyk helps
Estimating ink coverage
The four percentages give a rough sense of how heavy a colour is to print, which affects cost and drying.
Before you use the result
- This is a mathematical conversion, not a colour-managed one. True print colour depends on inks, paper and press profile, which a formula cannot know.
- The gamut differs: some vivid RGB colours simply cannot be reproduced in CMYK, and the conversion gives the nearest arithmetic result rather than warning you.
- It converts opaque colours; alpha has no meaning in CMYK.
- For a real print job, use the colour profile your printer specifies rather than this estimate.
- The values are rounded to whole percentages, as CMYK is normally quoted.
Questions about RGB to CMYK
Is this print-accurate?
No formula is. True print colour depends on inks, paper and press. This is a standard approximation for checking and estimating, not a colour-managed conversion.
Why can't some colours convert well?
CMYK has a smaller gamut than RGB, so vivid screen colours may have no exact ink equivalent. You get the nearest arithmetic result.
What is the K?
Key - the black ink. It is derived from the brightest channel, reducing how much coloured ink is needed.
Should I use this for a real print run?
As a starting point only. Use the colour profile your print house specifies for the final artwork.
Related tools
CMYK to RGB
Convert a CMYK colour to RGB in your browser, to preview a print colour on screen.
Hex to CMYK
Convert a hex colour to CMYK in your browser, to take a web colour toward print.
RGB to HSL
Convert an RGB colour to HSL in your browser, the model that makes colours easy to adjust.