I am 6ft, male, 12st 6 oz. I bought L, it fits perfectly. I have owned many alleged water proof/breathable jackets over the years (I have been continually cycling since the late 70s) and this one beats the lot. It is VERY waterproof and VERY breathable. Usually you have to take the breathability claims with a pinch of salt. I have ridden hard for 2 hours in pouring British winter rain and wind on multiple occasions. Never have I had a bin bag moment. I was sweating from my effort but not from overheating. This jacket rules. No water ingress, no overheating. Worth every penny.

Bought this based off its waterproof rating (60,000) and wore it for 7 hours in the rain to which it kept me dry throughout. Seemed really breathable and didnt have any 'boil in the bag' symptoms on the rides. The jacket cut is great with the right length tail to cover your butt. I usually wear Large (and bought the FS260-Pro Jetstream L/S Jersey in large which fits great), but this jacket was a bit too snug, with an additional base layer it wouldn't fit, so I returned for an XL, which is a better fit and maybe a tiny bit baggy. The roll up method has a loop to put the jacket into a roll then stick in your pocket, I found this a bit faffy and a good concept but in practicality, not that great. Rear pocket on the jacket is small, would ideally like one on the front breast for a phone. Overall , impressed with it!