I'm in the process of prepping some files for merchandising purposes i.e. mugs, hats, stickers, etc. I've always been a bit confused when it comes to CMYK and printing values and typically I am more comfortable prepping files for web. Anyway, I'm using the company's brand color guide and noticed I get two very different results in Illustrator when using the HEX code and the CMYK values. I want to make sure I export these at the correct color since they will be printed and I'm not sure what to do since these colors are so different. I've attached an example. Additionally, when I use a HEX > CMYK converter, I get the same values as I see in the brand color guide. Help, I'm so confused! Not sure how to properly export these at.
These online converters do no use color management as Adobe apps do.
They use a simple formula to calculate CMYK values that has nothing to do with how real inks on paper behave.
If the HEX values are what the color should look like, I would go for the conversion that Illustrator gives
But first find out what kind of printing process/press will be used and what CMYK color profile matches that process.
Use the CMYK values the client has provided, if they aren't concerned enough to give you a PANTONE swatch colour, the CMYK value is the best you can do. If they are willing to pay for colour proofs, I would suggest doing that. Do several swatches at once so the client can choose the closest colour. Use the CMYK values they have given you as a starting point. The print provider might/should be able to help you make a variety of swatches for the client.