Measurements vary, with studies that rely on self-measurement reporting a significantly higher average than those with a health professional measuring. 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.
Besides the natural variability of human penises in general, there are factors that lead to minor variations in a particular male, such as the level of arousal, time of day, room temperature, anxiety level, sport activity and frequency of sexual activity.
Human penises vary in size on a number of measures, including length and circumference when flaccid and erect. Diagram showing how to measure the length and circumference of an erect human penis
