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Human penis size

Penis size is of great concern to many men. Some consider having a large penisa mark of masculinity; others are concerned that their penis is too small to satisfy their sexual partners. These insecurities have led to many myths about penis size, and the creation of a whole industry devoted to penis enlargement.


  • 1 Data
  • 2 Perceptions
  • 3 Myths
  • 4 Micropenis
  • 5 Female preference
  • 6 Race and penis size
  • 7 Measuring a penis
  • 8 References
  • 9 See also
  • 10 External links


Regarding the length of the adult fully erectpenis (measured along the top of the penis from the groin to the tip), several studies have been performed. Those studies that relied on self-measurement consistently reported a higher average than those that had staff take the measurements.

  • An UCSFstudy by Wessells et.al. published in 1996found an average of 5.1 inches (13.0 cm). (Measured by staff)
  • A study by a Brazilian urologist found an average of 5.7 inches (14.5 cm). (Measured by staff)
  • A German study in 1996 also reported an average of 5.7 inches (14.5 cm). (Measured by staff)
  • A study conducted by LifeStyles Condoms during 2001 Spring Break in Cancúnfound an average of 5.9 inches (15.0 cm). (Measured by staff)
  • A study conducted by the Korean Consumer Protection Board (KCPB) at a college campus found an average of 6.1 inches (15.5 cm).
  • The longest erect penis on record is around 12 inches (30 cm). The shortest erect penis on record is under 1/2 an inch (1.3 cm), not counting cases where men are born without a penis.
  • A study conducted by the Journal of Sexology in Japan found an average of 5.1 inches (12.9 cm) (Measured by staff)
  • A study by the Jacobus Survey in India found an average of 4.0 inches (10.1 cm) (Measured by staff)

The majority of such studies are flawed due to the fact that someone with a below average sized penis is less likely to volunteer to be measured or allow himself to be measured than someone with an above average sized penis. This results in most studies concluding averages that are well above what the average really is.

Similarly, regarding the circumferenceof the adult fully erectpenis (with the measurement taken from the midshaft of the penis), several studies have been performed. Just as with length, those studies that relied on self-measurement consistently reported a higher average than those that had staff take the measurements.

  • An UCSFstudy by Wessells et.al. published in 1996found an average of 4.9 inches (12.5 cm). (Measured by staff)
  • A study by a Brazilian urologist found an average of 4.7 inches (12.0 cm). (Measured by staff)
  • A study conducted by LifeStyles Condoms during 2001 Spring Break in Cancúnfound an average of 5.0 inches (12.7 cm). (Measured by staff)
  • A study conducted by the Korean Consumer Protection Board (KCPB) at a college campus found an average of 5.0 inches.

There is an ongoing government study in India commissioned with the goal of helping reduce the high condomfailure rate there.

The flaccid penis is measured when fully stretched, from the belly to the tip, excluding the foreskin. The length of a stretched flaccid penis closely conforms to erect length.

Average stretched penile length at birth is about 4 cm, and 90% of newborn boys will be between 2.4 and 5.5 cm (0.94 and 2.17 inches). Limited growth of the penis occurs between birth and 5 years of age, but very little occurs between 5 years and the onset of puberty. The average size at the beginning of puberty is 6 cm with adult size reached about 5 years later. W.A. Schonfeld published a penis growth curve in 1943.

Regarding the length of the adult flaccid fully stretched penis:

  • Lee et.al. reported in 1980 an average of 13.3 cm (5.24 inches) with a standard deviationof 1.6 cm (0.63 inches)
  • Sutherland et al reported in 1996 an average of 12.4 cm (4.9 inches) (std. dev. 2.7cm or about 1 inch) in white men, an average of 14.6 cm (5.7 inches) in black men, and an average of 10.6 cm (4.2 inches) in Asian men. This study neglects to take into account height and weight, which may be the primary indicator of penis size.

The length of the unstretched flaccid penis is no guide to the size of the erect penis; indeed, some men with small flaccid penes may have larger erections than men with larger flaccid penis. When a man with a relatively large flaccid penis has a normal or below average length penis when he is fully aroused, or when a man with a relatively small flaccid penis has a normal or above average length penis when he is fully aroused, they are known by the slang terms "showers" and "growers" respectively.

Present environmental conditions play a role in the size of a relaxed flaccid penis, in particular cool temperatures. One general physiological response to cold is decreased circulation of blood to the appendages. As the size of the penis very much relies on blood supply, this results in a decreased flaccid size. The slang term "shrinkage" is sometimes used to describe this phenomenon; this was featured in a famous episode of Seinfeld. As humorist Garrison Keilloronce said, "At forty degrees below zero, all men are indeed equal."


In a 2005 study by the University of California Los Angeles, 45% of men responded they would prefer their penis size increased.[1] 84% of respondents rated their penis size as average to above average. There is a similar perception gap in women's perceptions of their breasts. (See: Human Breast Size) 70% desired more ample or rounder breasts.

Men may tend to misjudge the size of their penis relative to that of other men they have seen naked, simply because of the foreshorteningeffect obtained from always looking down at the penis from above. In addition, as Paul Fussellnoted in his memoirs, men who are overweight or have large stomachs may fail to allow for the partial concealment of the penis by their abdominal region. The build up of fat on the pubic bone above the penis may give a shorter appearance even though the length of the penis from the base is normal.

A survey by sexologistsshowed that many men who believed that their penis was of inadequate size actually had a normal-sized penis. Most sexologists believe that worries about penis size come from some other source of anxiety or perceived inadequacy.


In some cultures, mass hysteria involving the believed removal or shrinking of the penis has been observed. See penis panicfor a detailed discussion.

Many theories are held in popular culture, that it is possible to predict the size of someone's penis by observing other features. The features usually selected are

  • Size of hands
  • Size of feet, or shoe size
  • Size of nose
  • Height of a person

One of these theories says that the size of a fully erect penis is the length from the tip of a man's thumb to the tip of his index finger, when a 90° angle is made with those two fingers.

The suggested link between penis size, foot size and height has been investigated by a relatively small number of groups. Two of these studies have suggested a link between penis size and foot size, while the most recent report dismissed these findings. One of the studies suggesting a link relied on the subjects measuring the size of their own penis, which may well be inaccurate. The second study found statistically significant although "weak correlation" with the size of the stretched penis with foot size and height. A potential explanation for these observations is that the development of the penis in an embryo is controlled by some of the same Hoxgenes (in particular HOXA13) as the limbs. Mutations of some Hox genes that control the growth of limbs cause malformed genitalia (hand?foot?genital syndrome). However the most recent investigationfailed to find any evidence for a link between shoe size and stretched penis size. Given the large number of genes which control the developmentof the human body shape and effects of hormones during childhood and adolescence it would seem unlikely that an accurate prediction of penis size could be made by measuring a different part of the human body.

Other studies correlating the size of the human penis with other factors have given intriguing results. Notably one studyanalysing the Kinseydata set found that homosexual men had statistically larger penis that their heterosexual counterparts. One potential explanation given is a difference in the exposure to androgen hormones in the developing embryo.


Main article: Micropenis

A penis whose stretched flaccid length is more than approximately 2.5 standard deviationsbelow average size for the age group but otherwise formed normally is referred to in a medical context as a micropenis. Some of the identifiable causes are deficiency of pituitary growth hormoneand/or gonadotropins, mild degrees of androgen insensitivity, a variety of genetic syndromes, and HOX9 gene variations. Some types of micropenis can be improved with growth hormone or testosteronetreatment in early childhood. Penis-enlargement self-treatments are not effective for this condition.

A news post on New Scientistdated Dec 6, 2004reads "A new surgical procedure has allowed men with abnormally short penises to enjoy a full sex life and urinate standing up, some for the first time. Tiny "micro-penises" have been enlarged to normal size without losing any erogenous sensation, say UK doctors."

Female preference

One source of continued debate is the extent to which women actually prefer certain penis sizes. In the 2005 UCLA study, 85% of women said they were "very satisfied" with their partner's size.[2][3]

Recently, there has been greater media attention to the issue of penis size and women being more vocal about their preferences. Television shows such as Sex and the City and Ally McBeal popularized the penis size issue when characters in these TV shows stated their preference for well-endowed men and rejected men who had only average endowment. In one of these shows, a female character is portrayed crying in bed when she sees her boyfriend's penis for the first time and discovers that it is of only average length, as opposed to the large length she had expected and anticipated. On one episode of Sex and the City, the characters debate whether it's proper to dump a man because of displeasure over the size of his penis; they conclude that it's OK and at the end of the episode one of the women does indeed dump her boyfriend because she doesn't like the size of his penis.

The media image of women's preference may have had an impact on some average sized men, and caused even more damage to below-average sized men who are likely already self conscious. In recent years, penis pumps, pills, and other dubious means of penis enlargement have had increased sales.

Surveys of women's actual preference have consistently shown that penis size is only a priority for a minority of women, and some women dislike large penises. The media have been criticized for making "penis envy" into a male body issue equivalent to Cosmopolitan Magazine being criticized for their coverage of women's weight. Indeed, one episode of Sex and the City also shows a character expressing displeasure over her partner having too large a penis.

A Dutch study found in 2002 that 20-30% of women consider the size of a penis to be important.

Race and penis size

While it is commonly accepted that physical differences between races do exist (such as eye color, hair texture, noses, height, and hip width), the subject of penis size variation between different races has been a taboo since it could imply one race is "superior" or "inferior" to another. The question of race and penis size is therefore very controversial, and has not been definitively established. Although there is a stereotype that Africans are larger on average compared to Caucasians, and East Asians are smaller— there are no reliable data backing these perceptions. There have been many studies with claims of varying rigor—for example, the LifeStylescondoms study—but they are generally flawed by selection bias. Frantz Fanoncovers this subject in some detail in Black Skin, White Masks (1952), where he tends towards the view that the supposed positive correlation between large penises and African ancestry is a myth, a conclusion that he backs up with statistics. On the other hand, J. Philippe Rushtonhas published statistics claiming otherwise (Race, Evolution, and Behavior: A Life History Perspective, 1995).

Some diseases can affect and even increase penis size. For example sickle cell anemia frequently lead to priapismwhich, while it can damage the penis, has been known to trigger megalopenis conditions due to anoxic damage to the tunica albuginea.

Allen's Ruleand Bergmann's Rulepropose that warm-bloodedanimals (which includes mammals) in warmer climates tend to have a higher surface-area-to-volume ratio, to aid in heat dissipation. The size and thickness of appendages contribute to this ratio.

The cultural issues involved with the question of race and penis size are complex. For example, in American history, African-American slaves were often perceived as hyper-sexualanimals, as illustrated by the main character in Ralph Ellison'snovel "Invisible Man".

Measuring a penis

There are a variety of different ways to measure a penis; and there are a number of difficulties in doing so. First of all, a penis must be maximally erect to do so, and in a clinical setting this is difficult to achieve. At least one Brazilian doctor resorted to injecting penises, giving much more consistent results. Relying on self-reporting of penis size is problematic, since some patients exaggerate or are unable or unwilling to measure the penis correctly.

Length of a penis is typically measured with the subject standing and the penis held parallel to the floor. Measurement of length goes horizontally along the top of the penis from the patient's body to the tip. The length is usually quoted as either "bone-pressed" or "non-bone-pressed". "Bone-pressed" means that the ruler is pressed up along the pubic bone; this largely removes the problem of body fat interfering with the measuring process, and the penis will appear shorter for subjects with a high level of body fat.

Girth is measured by using a tape measure. It is often quoted as an average or at 3 places along the penis or just the penile head, in the middle of the shaft, at the base, or from the thickest part.


  • Wessells H, Lue TF, McAninch JW. "Penile Length in the Flaccid and Erect States: Guidelines for Penile Augmentation," Journal of Urology, Vol. 195, 995-997, 1996.
  • The Kinsey Institutepenis size bibliography
  • Sutherland et al. "The effect of prepubertal androgen exposure on adult penile length." Journal of Urology, Vol. 156(2S), 783-787, 1996.
  • Lee PA, et al. "Micropenis. I. Criteria, etiologies, and classification." Johns Hopkins Med J 1980; 146:156.
  • W.A. Schonfeld, Am J Dis Child 1943;65:135
  • Niels Lauersen, M.D. and Steven Whitney, "It's Your Body: A Woman's Guide to Gynecology", 3rd Edition 1983, p. 480 (Berkley Publishing Co.: New York), ISBN 0425099172
  • Bogaert, A. F., & Hershberger, S. L. (1999). The relation between sexual orientation and penile size. Archives of Sexual Behavior 28:213-221.(PMID:10410197)[4]
  • Mortlock DP, Innis JW (1997) Mutation of HOXA13 in hand-foot-genital syndrome.Nat Genet 15(2):179-80.(PMID:9020844)[5]
  • Goodman FR (2002) Limb malformations and the human HOX genes. Am J Med Genet 112(3):256-265(PMID:12357469)[6]
  • Shah, J. & Christopher, N. (2002) Can Shoe Size Predict Penile Length? BJU Int 90(6):586-7 (PMID:12230622)[7]
  • Siminoski K and Bain J (1993) The Relationship Among Height, Penile Length, and Foot Size. Annals of Sex Research 6(3):231-235
  • Kondo T, Zakany J, Innis JW, Duboule D.(1997) Of fingers, toes and penises. Nature 390(6655):29(PMID:9363887)[8]

See also

  • Penis envy
  • Phalloplasty

External links

  • Kinsey Institutepage on the penis
  • Penis size based on body parts Investigation into myth that Hands/feet/nose are an indicator of penis sizefi:Peniksen koko
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