Depends on the jacket and season. The more casual the jacket, the looser it is going to be. I have a tuxedo style jacket (size 50EU) that fits incredibly tight throughout, and another, tweedy sportjacket that fits perfectly through the shoulders and is actually a little roomy through the torso. I take a 50 in Jil Sander, Helmut Lang, and Costume National jackets, as well as Prada jackets, so I would say that the jacket will probably fit you. I take a uniform size because I believe that the jackets are designed to fit a certain way. IMO, a 50 Helmut Lang is just not supposed to fit as tightly as a 50 Costume National. Their runway shows reflect the differences in the designers' concept of how their clothes should fit.