To Measure Your Chest:
Raise your arms slightly and measure just under your arms. Be sure to cross over the shoulder blades and the fullest part of the chest. For example, if you have a 38" chest, you would wear a 38" suit size.
To Confirm Your Suit Size:
Measure your waist or the waistband of a comfortable, well fitting pair of pants and add 6 inches. For example, a suite size 42" comes with a 36" waist trouser.