You can find more information regarding the size of products on each of the product pages of this site. The chart below can be used to determine your size.
Collar: (Men's formal shirts only) Measurement around base of neck (the lowest point of the neck). Number of inches equals the neck size you should order.
Chest: Measure fullest part of chest, keeping tape parallel to the floor. (If you have help, leave arms relaxed, down at sides.)
Waist: Measure around waist at the height you would normally wear your trousers. Or measure across the waist of a pair of trousers that fit you well and mulitiply by two.
Inside Leg: Take a pair of trousers that fits you well. Measure from one crotch seam to the bottom of the leg.