Chest/bust
Raise your arms slightly and measure around your body. Be sure to measure
the fullest part of your chest/bust, keeping the tape parallel to the ground.

Waist
Measure around your waist where your pants usually fall. Keep one finger
between the tape and your body to ensure an accurate fit.

Sleeve
Place your hand on your hip with your arm bent at a 90 degree angle. Measure
from the middle of the back of your neck, across your shoulder and down your
arm to your wrist.

Length
Find a t-shirt that fits you. Measure from the center of the back collar of your
favorite t-shirt to the end of the shirt, this is your desired length.