Taking measurements correctly

Height
Measure from the crown of your head to the soles of your feet. The best way to do this is to stand in a doorway.
Arm length
Measure from the shoulder to the wrist.
Bust circumference
Measure around the fullest part of your chest.
Underbust circumference
Measure around your body below the bust.
Waist circumference
Measure once around your waist, making sure the tape measure is not too tight.
Hip circumference
Measure around the fullest part of your hips.
Leg length
Measure along your leg from the crotch to the floor.
All measurements in the size charts are body measurements. For this reason, it's important that you measure close to your body. For best results, wear your underwear only and stand in a relaxed way while taking your measurements. Get someone to help you to ensure the measurements are as accurate as possible.