Purchasing a 4X shirt can be somewhat vexing, as manufacturers and retailers do not offer industry-wide standards, but a range of measurements taken in inches. Some items, such as button-front dress shirts, will list measurements along with a 4X sizing label for easier selection.

A men's shirt has four main measurements. Neck measurements are taken at the base of the neck. Chest and waist measurements are taken under the armpits and at the navel. Sleeve measurements are taken by placing your hand on your hip and measuring the outer length of your arm from collar to wrist. Tall measurements are defined as a person over 6-foot-4 in height. Tall torso measurements can be taken from armpit to hip and compared with standard shirt lengths.

Necks and sleeves offer the least measurement variation at 4X. Neck sizing ranges fall between 22 and 23 inches while sleeves range from 37 to 38 inches. The width of the sleeves are cut proportional to the length, and arm holes are cut in proportion to chest size. Typically, tall sizing has no neck and sleeve measurement variation.

Size 4X chest measurements commonly fit those between 57 and 60 inches around the widest part of the rib cage. Dress shirts will narrow toward the hip to fit a measurement of 56 to 59 inches. Standard cotton T-shirts use a width measurement based on the chest and will not taper at the hip. Tall sizing will be approximately 2 inches longer in the torso than standard length.

If your measurement range falls within two sizes, select the size that fits your neck with room for one finger in the collar. This may mean a larger chest and sleeve size, which can be taken in by a tailor.