("Penis length" redirects here. For differences in penis length among non-human species, see Penis § In different animals.) The most accurate measurement of human penis size can be derived from several readings at different times since there is natural minor variability in size depending upon arousal level, time of day, room temperature, frequency of sexual activity, and reliability of measurement. When compared to other primates, including large examples such as the gorilla, the human penis is thickest, both in absolute terms and relative to the rest of the body.