I am 5'7" 128lbs. I purchased a TM so the body would be a little longer as well as a RM to compare. I have long arms and sometimes that is a problem with the sleeves. The M fits perfect in both ( T and R) as far as the body goes. Semi fitted , but not too tight. The arms however are another story ….... In both jackets the arms are very generous and not much difference in the length of the arms - I would have given this 5 stars if the arms were slimmer , they are too generous in width . Looking back at the photo you can see that in the model. You would wear this jacket with a fitted athletic top- definitely not a sweater , so the generous arm width makes no sense. I'm on the fence about keeping it. Definitely long enough arms and I like the little longer length fit in the T. Perfect for walks , hiking , any outdoor activity, and really nice zipper pockets. If your arms are not slim , you will love everything about this jacket.