Take body measurements
Neck Measurement

Wrap the tape measure around your neck; about an inch and a half from where your neck meets your shoulders. This may also coincide with the bottom of your Adam's apple. Do not leave any space between your neck and the tape. Make sure the tape is level and not held at an angle. Insert the width of one finger.
Shoulder Measurement

Your back should be straight, but your shoulders should hang naturally in a relaxed position. Place the tape measure from the tip of one shoulder to the other, touching the base of your neck.
Chest Measurement

Slide the tape so that it circles your chest and just under your armpits.
Place it firmly around the widest part of your chest, which is often at or above the nipple line.
Waist Measurement

Hold the end of the tape measure at your belly button and circle it around your waist.
The tape measure should be parallel to the floor and fit snugly around your torso without digging into your skin. Insert the width of one finger.
Shirt Length

Place the end of the tape measure at the shoulder seam touching the collar.
With your arm relaxed, measure the length down to the crotch of your pants.
Sleeve Length
The tape measure should be held at shoulder height and extended along the outside of your bent arm down to your wrist, where you want the shirt cuff to end.
Armhole Circumference

The tape measure should be held at shoulder height and extended around the entire circumference of the arm/armpit. Allow for one finger's width of slack.
Arm Measurement

When measuring your bicep, your arms should be completely relaxed and hanging at your sides.
To ensure your shirt fits correctly, the bicep measurement should be taken around the thickest part of your bicep. This point will likely be high on your arm, only about 5 cm below your armpit.
Insert the width of one finger.
Hip Measurement

Hold the end of the tape measure at your hip bone and circle it around the widest point.
The tape measure should be parallel to the floor and fit snugly around your torso without digging into your skin. Insert the width of one finger.
Forearm Measurement

When measuring your forearm, your arms should be completely relaxed and hanging at your sides.
To ensure your shirt fits correctly, the arm measurement should be taken around the thickest part of your forearm. This point will likely be just below your elbow.
Insert the width of one finger.
Wrist Measurement

Measure the circumference of your wrist, inserting one finger to allow for a little slack.
