I am 5‘8“170lbs, with a 44 inch chest and 33 inch arms, and I haven’t seen the inside of a gym in many years.I bought two of these, one large, and one medium. The large would leave me room if I wanted to wear a sweater underneath, and the small is a bit snug, but the sleeves fit better.They are very nice, seem to be well-made and warmer than I expected. Excellent for crisp spring mornings.