How to Measure Your Body Size
Neck
To measure your neck size, put a measuring tape around your neck where the collar would normally be. Put one finger under the tape measure to provide an allowance for some comfort.
Chest
To measure the circumference of your chest, place one end of a tape measure at the fullest part of your chest and wrap it under your armpits and back to the front area of your chest.
Waist
To measure your waist, use a tape measure and wrap it around your waist like a belt. Your waistline is located below your rib cage and above your belly button.