Let's measure your Arms
Relax your arms. Measure the length in two steps. Start from the bone at the top edge of your shoulder and measure to your elbow. Hold the tape measure there and continue measuring to your wrist, just below your wrist bone.
Let's measure your Crotch
Locate your waist by placing four fingers beneath your belly button and wrapping the tape measure level around your waistline just below your fourth finger. Mark the center front and center back points and remove the tape measure. Hold the metal tip of the tape measure at the front point. Measure from here to the opposite point on your back, keeping the tape measure centered and snug