The suit can make the man, so you want to be sure that you measure yourself correctly to purchase the right size. Typically, suits come as a pair with both a jacket and trousers. Your chest and waist measurements and your height determine your size. A regular suit comes with trousers that have a 6-inch difference from the waist size. Athletic suits have 8-inch difference, while portly suits have a 4-inch difference. If there is a large difference between your pant size and your jacket size, consider purchasing suits from stores that allow you to mix and match your jackets and trousers.
Wrap the tape measure around your chest to take that measurement. The tape measure should be parallel to the floor and go across the broadest part of your chest. Take this measurement in inches.
Subtract 2 inches to get your suit size.
Use your height to determine whether you need a short, regular or long jacket style. If you are 5 feet 6 inches or less, your suit size will have an "S" next to it for "short." Those standing from 5 feet 7 inches to 5 feet 11 inches will wear a regular or "R" suit. If you are taller than that, you should purchase a "L" or "long" size. For example, if you are 5 feet 9 inches with a 42-inch chest, your suit size will be a 40R.
Measure your waist and inseam to get the correct size trousers. Wrap the tape measure around your waist to determine that size. The inseam is the measurement from the crotch of your trousers to the length that you want the trousers to be.
All bodies have slight variations. A tailor can adjust your suit to fit you perfectly.