This document provides instructions for measuring muscle girth in the biceps and calves using a tape measure. For biceps, the tape is wrapped around the largest part of the muscle while it is contracted. For calves, the tape is wrapped around the highest part of the leg while standing with the foot on a chair to avoid muscle contraction. Taking multiple measurements and using the median ensures accuracy. Muscle girth measurements are a basic, inexpensive method to determine potential muscular issues and assess proportions of the body.