Measure under your arms, around the fullest part of your chest.

Measure under your natural waist-line, keeping the tape slightly loose.

Measure under your hips, keeping the tape slightly loose.

With legs slightly open, measure around the fullest part of your thigh.

Hold the tape at the center back of your neck. Measure across your shoulder to your elbow and down to the edge of your wrist. The total lenght is your sleeve lenght.