Nope. In fact, any jacket or suit that comes in S/M/L sizes should be avoided.
Now, I'd say based on a size M, youd probably be anywhere from a 38 to a 44... But you really just need to try them on, there is no way to say "Oh, you are a size 42." Furthermore, every manufacturer's sizes are different--sometimes different within the same maker but different models. For example, I have coats from size 38 to 41 that all fit me roughly the same.