Great fit, fabric and details!
I bought this originally as a 38R (my suit jacket size) but I bought a 40R because I thought the 38R was too tight in the shoulders/chest for me, in terms of layering underneath a suit jacket. If you want to wear this jacket with out a suit, get your suit jacket size. Size up if you do. Moving on from fit, this thing is fantastic. The wool is so soft you'd swear it was mixed in with cashmere. The horn buttons look beautiful and the peak lapels are sized well. Not too slim and not flared out either. One thing, this jacket is nicely tapered and drapes beautifully. It is such a joy to wear. Bonobos did a wonderful job designing this jacket. I hope to keep it for years to come!