Men shopping for a suit often request — and many times end up purchasing — the wrong size. Sometimes, blame for the mistake must be shared by the salesperson, whose constructive guidance is indispensable, especially if the customer is shopping alone. With the help of your wife or a friend to take and record your measurements, however, you may ensure that when you begin shopping for a suit you are armed with the necessary information.

The first and most important measurement is the chest. Wearing only a T-shirt, run the tape measure around your chest under the armpit and across the nipples. The chest size of the average American man is 42 to 44 inches. That is the size of the suit that you need to buy. If your chest size is 43, go up to a size 44.

Sleeve length is a little more tricky. You must have help with this step. At the base of your neck and at the top of the spine there is a protruding bone. Place one end of the tape measure at that bone, measure across to the shoulder and down the outside of your arm. At the wrist bone add another inch and that is your sleeve measurement. The average sleeve length among American men is 32 to 33 inches. With a chest size of 44 and a sleeve length of 32 or 33, "44 Regular" would be the size to buy.

Pants are generally 8 inches smaller in the waist than the chest size. Do not buy a suit by any other measurement than the chest size. The suit that fits correctly in the shoulders can be adjusted to fit correctly everywhere below.

To measure the inseam, place the end of the measuring tape up in the crotch and measure down to 1 inch off the floor. The average inseam among American men is 30 to 32 inches, although 34 is not an uncommon inseam.