This is the most sought question among both men and women. But we all know that every single man will have different penis length and girth. Many Doctors suggests that size really doesn't matter as long as the penis is greater than 3 inches which is the minimum length for conception. These days men and women are obsessed with the bigger penis and dreaming fantasies from the ubiquitous porn. But there is no such report or study proving that bigger the penis, higher the satisfaction.
Yet we are curious about these kinds of question. To your luck, there are answers to your curiosities. There are few studies on the average length and girth of the penis.
"One of the latest large-scale studies took place in 2013, when Debby Herbenick, Ph.D., a sex researcher and educator at Indiana University authored Erect Penile Length and Circumference Dimensions of 1,661 Sexually Active Men in the United States."
The renowned sex educator has done some astounding research by collecting self-reported data from 1661 men. She also incentivized those men to do the measuring precisely and offered them best ondoms online in India to measure the perfect fit simultaneously. From those data, Herbenick extrapolated that the average length of a man's penis is 5.7 inches and the average girth of a man is 4.81 inches when erect.
Another study published in BJU International compiled a collective data from 17 other studies involving 15,521 men measuring their penis to determine the average girth and length of the penis. In this study, all the penises were measured using the standard procedure by the health professionals to ensure the results were as accurate as possible.