CMYK to RAL or PANTONE conversion

A client needs to produce a large logo for their front office and the production company requires us to convert the CMYK 40,48,77,17 to RAL or Pantone. I have never been faced with such a request and not sure how to approach this correctly? The logo is black text + an icon in this single CMYK code (flat color). thanks

Answer

Hum. If you have not defined a color profile you can not know for sure.

Find out what is the color profile they normally use on that color patch. Probably one for a coated paper. Swop2? Fogra 27? Gracol something?

Then fill a square with the CMYK values and take a measure of it on, let's say Illustrator using for example Pantone+ Solid Coated library.

It gives around P 874 C with SWOP2

But to tell you the truth I do not like the way Illustrator handles this libraries because I do not know if I tweaked the library or not. I am so dumb handling Illustrator but this is a poorly UX on the program.

Corel has a more direct approach. If I assign the same values gives P 872 C.

So, in reality, you need to grab a physical color guide and refine your decision.