Read this before using the number
There is no correct conversion from hex to CMYK. Screen colour is light being emitted; print colour is ink absorbing it. The mapping between them depends on the specific ink set, the paper, the press and an ICC profile — none of which a web page knows.
What every converter on the internet shows, this one included, is the naive formula: subtract each channel from one, pull out the common black. It is a reasonable orientation and it is not a print specification.
When the approximation is fine
- Judging roughly how much ink a colour will need.
- Spotting that a vivid screen colour is out of gamut and will disappoint in print — bright cyans and oranges are the usual casualties.
- Filling a field in a mockup that nobody will send anywhere.
When it is not
Anything going to a printer. Ask them for the profile, convert in software that can use it, and proof it. A brand colour in particular should be specified as a Pantone or a measured CMYK build, not derived from a hex value.
Questions
Is this accurate enough to print from?+
No. There is no correct hex-to-CMYK conversion without an ICC profile, the ink set and the paper. This is the naive formula every web converter uses — an orientation, not a specification.
Why does my vivid colour look dull in print?+
Because it is outside the CMYK gamut. Bright cyans, oranges and greens are the usual casualties; the number here will not warn you, but a proof will.
What should I do for real print work?+
Get the profile from the printer, convert in software that can apply it, and proof it. For a brand colour, specify a Pantone or a measured CMYK build instead of deriving one.