This girth measurement is usually taken on the right side of the body. The subject holds the arm out with the palm facing upwards. The measurement is taken along the forearm at the point of the largest circumference. The maximal girth is not always obvious, and the tape may need to be moved up and down along the forearm to find the point of maximum circumference, which will usually be found closer to the elbow. When recording, you need to make sure the tape is not too tight or too loose and is lying flat on the skin.