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Studies Distribution of penis sizes by length. Some environmental factors in addition to genetics, such as the presence of endocrine disruptors, can affect penis growth. Limited to no statistically significant correlation between penis size and the size of other body parts has been found in research. Flaccid length is a poor predictor for erect length. An adult penis that is abnormally small but otherwise normally formed is referred to in medicine as a micropenis, with the cutoff usually being defined as around 3 inches (7.6 cm). Flaccid penis length can sometimes be a poor predictor of erect length. A 1996 study of flaccid length found a mean of 3.5 inches (8.9 cm) when measured by staff. As of 2015, a systematic review of 15,521 men, who were measured by health professionals rather than themselves, concluded that the average length of an erect human penis is 13.12 cm (5.17 inches) long, while the average circumference of an erect human penis is 11.66 cm (4.59 inches). Measurements vary, with studies that rely on self-measurement reporting a significantly higher average than those with a health professional measuring. Most human penis growth occurs in two stages: the first between infancy and the age of five and then between about one year after the onset of puberty and, at the latest, approximately 17 years of age. 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, ambient temperature, anxiety level, physical activity, and frequency of sexual activity. Human penises vary in size on a number of measures, including length and circumference when flaccid and erect.
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For other uses, see Big Dick (disambiguation).ĭiagram showing how to measure the length and circumference of an erect human penis