How to measure
Measure and fit your collar shirt. Lay the collar flat and measure from the center of the collar button to the far end of the button hole. The measurement in inches is your collar size. (Alternatively, measure the bottom of the neck.)
With both arms relaxed on both sides, measure the chest around the armpits, the highest part of the chest and shoulder blades, keeping the belt parallel to the ground.
Measure the normal riding position of the waist, underwear and pants. Put a finger between the tape and the body.
Stand with high heels and measure around the largest part of the hips, keeping the tape parallel to the ground.
Bend your elbows 90 degrees and place your hands on your hips. Fix the tape to the center of the back of the neck. Measure shoulder to elbow, then wrist. The total length in inches is your sleeve length.