Got a quick question about the difference between CMYK in Adobe Illustrator and the Web generators.

I'm just starting out with Adobe Illustrator to create my own logo and brand. The document type is in CMYK. I've selected a couple of primary colours in CMYK. One of them is blue. When i check the CMYK code on the web, the color is totally different. How come?

Picture of my primary color in Illustrator:

enter image description here

Picture of my primary color on one of the web generators:

enter image description here

As you can see even the HEX code is different. When i want to print out for example a business card, which CMYK code do i provide to my print manufacturer?

  • Hex is RGB.... RGB is not CMYK. This isn't a "quick question" because understanding the gamut and variances between two entirely different color models (RGB vs CMYK) is not a "quick" answer. Your images show only one CMYK color breakdown. – Scott Jan 31 at 21:32

Check the CMYK code on the web

Who's web? There is no such thing as "the web" You are using someone's specific website. Let's say, Pantone.

Ok, so let's take it as an example. Pantone is an American company. In my little experience and some tests I did some time ago, Pantone's published conversions were using American color profiles. I have to experiment with modern American profiles, like Gracol, but when I did the tests, SWOP v2 matched the conversions.

This is something I have always criticized about Pantone's website. They do not publish what color profiles they are using for the color model conversions. Probably because they want to keep portraying the colors as "universal" or "independent".

This leads to another part of the answer... What color profiles you are using? and What color profiles are being used on the website you explored?

If the website you are using has no declared color profiles, do not "trust" it.

So. To define a color for a corporative brand design, use a color catalog, like a Pantone color bridge.

If you do not have one, define the colors as CMYK but declare what color profile you are using, and this depends on the region you are in. US, Europe, etc. Some color profiles widely accepted are Fogra's.


The quick answer: Numbers are not colors. It is what you do with those numbers that matters.

CMYK is a device specific color space. It makes no sense to have a CMYK conversion that does not specify what specific standard or device space you are emulating.

Likewise there is no RGB color either. But atleast in RGB land we can make a guess that unless specified that the space is sRGB.

Unless you have told either application what your colorspaces factually are, then neither of them are correct. To do this you need to measure your monitor and get the correct measurement/calibration info from your printer

  • I would like to add that this entire subject is very very complicated. Much more complicated than many of the academic subjects that are considered complicated pale in comparasion. Mainly because you have to deal with things that dont translate well into common language, since you need to see beyond what people normally consider reality. – joojaa Feb 1 at 7:06

The printshop has a theoretical possibility to print what you see on Illustrator's screen. It's possible if

  • your document color mode is CMYK and
  • your working CMYK color profile is what the printer says you should use to make your system to know what printed colors CMYK numbers actually mean and
  • you use CMYK colors in your shapes and
  • your monitor shows right the color space which is your working RGB color space (typically =sRGB)

Do not believe any web based RGB-CMYK conversions which do not ask the color profile of your CMYK printing process. They assume CMYK system which can produce all RGB colors. Practical CMYK printing processes can output only a part of colors that usual RGB screens can show.

You can find easily RGB to CMYK conversion calculators which perform 1:1 conversion without asking any color profiles. With them all RGB colors can be written as CMYK numbers. It's not wrong if one assumes that the printing process can output all RGB colors i.e. the printer has the same color space as the screen. The result is false for all real CMYK printing processes, but as an alternative way to present RGB colors it's perfect. In that case the conversion result from RGB to CMYK isn't unique, it depends on how much black (=k) is used.

One example of calculator which performs the "know nothing of real CMYK printing" - conversion: https://www.rapidtables.com/convert/color/rgb-to-cmyk.html It solves the "how much black" ambiguity by adding as much black as possible. Some other calculator get different CMY numbers by assuming less black, for ex. 0%.

In Illustrator you very likely have some default color settings which try to work realistically and produce printable CMYK numbers. It's useless if the settings do nor respect what the actual printing process needs.

A couple of suggestions:

  1. Ask your printer what color settings you should use in Illustrator to see what you will get

  2. Learn Adobe's guidance how to use Color Management to get consistent colors

CMYK printing is a gamble if you do not understand color management. People pay long penny to Adobe because its programs are designed to understand CMYK printing. It would be a lot cheaper if usable print results were possible with GIMP or Inkscape (which know nothing of CMYK printing).

  • Comments are not for extended discussion; this conversation has been moved to chat. – PieBie Feb 1 at 8:32

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