Place the tape measure at the center front of your torso and wrap it around the narrowest part of your waist until it meets the spot where you began. Be careful not to over-tighten the tape measure, but leave enough slack for the width of two fingers.
Measure your chest at the broadest portion of your torso. Place the tape in the middle of the chest and wrap it around your body, passing under both arms until it meets the spot where you began, keeping the tape parallel to the floor, Again, leave enough slack in your tape to fit the width of two fingers.
Place the measuring tape on the bone at the center base of your neck and extend horizontally to the shoulder point. From there, run the tape vertically down your arm, extending as long as you wish your sleeve length to be.