Compared to other primates, even larger primates such as the gorilla, the male humangenitalia are remarkably large. The human penis is both longer and thicker than that of any other primateSmall, Meredith F., What's Love Got to Do With It? The Evolution of Human Mating, 1995, Anchor Books, cited in Andrew L. Casad. The Sexual State of Human Nature (1998), as are the testesRussell, Robert Jay, The Lemur's Legacy: The Evolution of Power, Sex, and Love, 1993, G. P. Putnam, cited in Andrew L. Casad. The Sexual State of Human Nature (1998). Penis size is of great concern to many people. Some consider having a large penis a mark of masculinity; others are concerned that their penis is too small to satisfy their sexual partners. These insecurities have led to many erroneous beliefs about penis size, and the creation of a whole industry devoted to penis enlargement.
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 with drugs to induce an erection, 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 patients base to the tip.
Girth is measured by using a tape measure. It is variously quoted as an average, or at 3 places along the penis, or just the penile head, or in the middle of the shaft, at the base, or from the thickest part.
There have been several studies regarding the average size of the human penis. The majority of such studies could be unreliable due to self-selection bias: men with a smaller than average penis might be less likely to allow themselves to be measured, while men with a larger than average penis might be more likely to allow themselves to be measured. It is unknown if this conjectured self-selection bias has been confirmed by any studies, or if any studies have attempted to account for potential self-selection bias regarding penis size.
Size at birth
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 in). 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. Schonfeld, W. A. (1943). Primary and secondary sexual characteristics: Study of their development in males from birth through maturity, with biometric study of penis and testes. American Journal of Diseases of Children, 65, 535.
Erect length
Frequency graph of LifeStyles data
Percentile plot of LifeStyles data
Regarding the length of the adult fully erect penis (measured along the top of the penis from the groin to the tip), several studies have been performed. Studies that have relied on self-measurement, including those from Internet surveys, consistently reported a higher average than those which used medical or scientific researchers to perform the measurements.
Academic and Scientific Studies * A study published in the September 1996 Journal of Urology concluded that average erect length was 12.9 cm (5.03 in). (Measured by staff)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. * A study by a Brazilian urologist found an average of 14.6 cm (5.75 in). (Measured by researchers) * A study conducted by the Korean Consumer Protection Board (KCPB) at a college campus found an average of 15.5 cm (6.1 in). * A German study in 1996 also reported an average of 14.5 cm (5.7 in). (Measured by researchers) * A study conducted by LifeStyles Condoms during 2001 Spring Break in Cancún, Mexico found an average of 14.928 cm (5.877 in) with a standard deviation of 2.096 cm (0.825 in). (Measured by staff)
Low temperatures affect the size of the flaccid penis. One general physiological response to cold is decreased circulation of blood to the extremities, which includes the external genitals. The penis will often shrink further as a result. The slang term shrinkage, which was largely popularized by the 1994 episode "The Hamptons" of the NBCsitcomSeinfeld, is sometimes used to describe this phenomenon.
In a 2005 study by the University of California, Los Angeles, 45% of men responded they would prefer their penis size increased. 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.)
Men may tend to misjudge the size of their penis relative to that of other men they have seen naked, simply because of the foreshortening effect obtained from always looking down at the penis from above. In addition, as Paul Fussell noted in his memoirs, men who are overweight or have large stomachs may fail to allow for the partial concealment of the penis by their abdomen. The accumulation 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 sexologists showed 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.
Past perceptions
In ancient Greek and Roman art, it is common to see the male genitalia to be smaller than one would expect for the size of the man.{cite web
last = Cecil
first = Adams
title = Why does so much ancient Greek art feature males with small genitalia?
accessdate = 2006-08-05 }} Renaissance art also followed this aesthetic; note Michelangelo's David. This was due to the belief that an uncircumcised small penis was desirable in a man, whereas a long, thick, circumcised penis was viewed as comical. This may have had to do with the Greeks' adoration of an undeveloped body or the actual size of real models who stood in cold studios.
In some cultures, mass hysteria involving the believed removal or shrinking of the penis has been observed (genital retraction syndrome).
Many theories are held in popular culture, that it is possible to predict the size of someones penis by observing other features. The features usually selected hands, feet, nose or height. One urban legend suggests 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 these two digits.
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 Hox genes (in particular HOXA13 and HOXD13) as the limbs develop. Mutations of some Hox genes that control the growth of limbs cause malformed genitalia (handâ€"footâ€"genital syndrome). However the most recent investigation failed to find any evidence for a link between shoe size and stretched penis size.{cite web
accessdate = 2006-08-05 }} Given the large number of genes which control the development of 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 study analysing the Kinsey data set found that homosexual men had statistically larger penises than their heterosexual counterparts. One potential explanation given is a difference in the exposure to androgen hormones in the developing embryo.
According to Dr. Louanne Cole Weston, in a May 2002 report by WebMD, several misconceptions have developed surrounding penile-vaginal intercourse. Cultural preferences may have enlarged the importance of deep vaginal penetration in obtaining female orgasm.
The vagina itself is a very elastic environment which can expand on average to ~10 cm (4 in) in diameter during delivery, yet it also easily retains a tampon. It will generally accommodate and adjust to the entity it surrounds within a minute or so, although discomfort can sometimes be experienced with unusually large diameter entities, but the vagina can adapt over days to weeks, within reason.
The perception of the vaginal canal as being the primary source of orgasmic stimulation may be exaggerated in many cultural circles. The most sensitive area of the vagina is the section closest to the outside of a woman's body, which is roughly 10 centimeters (4 inches) in length. Given that the average penis size is above this length, most men should be able to easily reach and stimulate these erotic nerve endings.
In stark contrast, minor surgery without anesthetic can be conducted on the inner portion of a woman's vagina without discomfort. Most women attest to a feeling of being "filled up" by larger than average penises, yet few can claim to feel erotic sensations in the deeper regions of the vagina. In fact, stimulation of the G-spot may be more effective if the man's penis is slightly shorter than average, as this highly sensitive area of the vagina is located closer to the opening of vagina than to the recesses of its canal.
Long penises (over ~20 cm (7.5 in)) are susceptible to rubbing on, or striking the cervix, which has been described as being a similar sensation to being punched in the stomach. Thus very long penises often cannot normally be fully inserted. The exact depth depends both on the woman as well as the arousal of the woman -- during sexual intercourse the vagina lengthens rapidly after initial insertion from about 13 - 19 cm (5.1 inches to 7.5 inches); but the final and initial depths vary from woman to woman ±5cm (±2 in). Many women can accommodate longer penises (up to a point) when fully aroused as the vagina tents (further expands) while the cervix retracts; meaning with the right penetration angle long penises will slide over or under cervix without directly hitting it. More foreplay (to produce full arousal) is generally needed to ready a women for penetration of a long penis.
On the other hand stimulation of the G-Spot may be more effective if the man's penis is thicker than average, since the pleasure sensations from this area are activated primarily by pressure. A thicker penis may provide more friction against the vestibular bulbs, which are located in close proximity and anteriorly on either side of the urethra. Additionally, some claim that if a penis is thick enough compared with the vaginal opening, i.e. vulva, stretching will occur. This stretching can supposedly cause the clitoral hood to pass back and forth across the clitoris, which would provide additional stimulation of this large concentration of nerve endings. This stretching is claimed to pull the clitoris down into the path of the thrusting penis, causing it to make contact with, and rub across, the top or dorsal section of the penis. This may facilitate even greater clitoral stimulation.
Women have confirmed in surveys the primary focus of the clitoris in sexual stimulation. Roughly three-quarters of women surveyed have reported difficulty reaching orgasm by vaginal intercourse alone, and just 7% are able to do this on most occasions. Many report requiring simultaneous clitoral stimulation -- regardless of the size of the inserted object.
A penis whose stretched flaccid length is more than approximately 2.5 standard deviations below 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 hormone and/or gonadotropins, mild degrees of androgen insensitivity, a variety of genetic syndromes, and variations in certain Homeobox genes. Some types of micropenis can be improved with growth hormone or testosterone treatment in early childhood. Penis-enlargement self-treatments are not effective for this condition.
A relatively higher incidence of micropenis has been found in several Asian populations, including Japanese, Chinese (of varying ethnicity) and Vietnamese samples, considered due to a higher mutation rate for the SRD5A2 gene, which encodes for the enzyme 5{alpha}-reductase-2 and plays a role in male sex differentiation (Sasaki et al. 2003). The mutation led to decreased expression of the enzyme, which in turn results in penises with erect lengths of -2.5 standard deviations. In the case of the Japanese sample, hormone treatments were also studied and found to be effective, resulting in penis lengths at nearly the average of age-matched Japanese controls.
The smallest penis on record was reported in a medical journal by researchers from Oxford University's Department of Physiology, Anatomy and Genetics. The researchers noted that patient "Alfred," a male musician, in his early 30s, from Oxfordshire, UK., "possessed a penis almost indistinguishable from a clitoris." Currently there is much debate in the medical community as to whether patient "Alfred" is actually male or intersexed.
A news post on New Scientist dated December 6, 2004 reads "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."
One source of continued debate is the extent to which heterosexual women actually prefer certain penis sizes. In the 2005 UCLA study, 85% of women said they were "very satisfied" with their partner's size.[1]
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 HBO's Sex and the City, a female character is portrayed crying in bed when she experiences her boyfriend's penis for the first time and discovers that it is below average length, as opposed to the large length she had expected and anticipated. In the same episode 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 that one of the women does indeed dump her boyfriend because she doesn't like the size of his penis, even though earlier in the episode she reveals that she thinks she loves him.
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, though the penis is described in hyperbolic terms and implied to be something of impossibly gargantuan proportions.
A study published in BMC Women's Health, surveyed women's preferences concerning penis size and concluded that width rather than length is the most important factor of sexual stimulation.[2]
Differences in average penis size between different races has been a subject of considerable controversy since it could be taken to imply that one race is "superior" or "inferior" to another.
The cultural issues involved with the question of race and penis size are complex, with both larger and smaller penises used as justification for regarding other races as inferior; as evidence of an oversexed and brutish animal nature in the former case, or of sexual inadequacy in the latter case. In general, there is a tendency to see the penis size of one's own group as the "right" size, compared to those of others.
There is considerable debate as to whether specific racial variations in penis size exist, and if they do, whether observed variations can be explained in terms of other factors such as correlations of penis size to body size. In any case, within-group variation in penis size (±30%, see above) seems to be considerably larger than claimed between-group variation of average penis size (±4%, see below). *One of the earliest researchers on the subject, Frantz Fanon, covers 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 erroneous, a conclusion that he also supports with statistics. *One study by the controversial Canadian psychologist J. Philippe Rushton states that "[p]enis size also varies moderately across populations, being largest among African populations, smaller among European populations, and smallest among East Asian populations,..." [3] *Rushton has also stated that the World Health Organization specifies 5.3 cm wide condoms for Africa, 5.2 cm wide condoms for Europe, and 4.9 cm condoms for Asia. [4] *According to a more recent international study, Family Health International states "The World Health Organization bases its specifications for condom width on consumer preference and penis size, citing three studies. Taken together, the studies show significant variations in penis size within all population groups, but also indicate that men of African descent on average have a slightly wider and longer penis size, Caucasian men have a medium size, and Asian men a slightly narrower and shorter size." WHO Global Programme on AIDS. Specification and Guidelines for Condom Procurement. Appendix VII, Regional or Ethnic Differences in Erect Penis Size. Geneva: WHO, 1995. Cited in [5] *A 2001 study on penis size among young Italian males in a random group of 3,300 young men ages 17-19 showed "median values of penile dimensions recorded in the present study are flaccid length 9.0 cm, flaccid circumference, at the middle of the shaft, 10.0 cm, and stretched length 12.5 cm. We also observed that the penile dimensions are highly correlated with height and weight." Roberto Ponchiettia, Nicola Mondainia, Massimiliano Bonafèb, Filippo Di Loroa, Stefano Biscionia, Lorenzo Masieria. Penile Length and Circumference: A Study on 3,300 Young Italian Males. European Urology 2001 Feb:39(2):183-6.Abstract *In 2003 "Studies on self-esteem of penile size in young Korean military men." showed results as shown: "The mean flaccid length, flaccid circumference, stretched length and fat pad depth of the 123 subjects were 6.9±8 cm, 8.5±11 cm, 9.6±8 cm and 1.1±4 cm, respectively." Asian J Androl. 2003 Sep;5(3):185-9 *A 2002 Survey, "Can shoe size predict penile length?" To establish if the 'myth' about whether the size of a man's penis can be estimated from his shoe size has any basis, in fact. Two urologists measured the stretched penile length of 104 men in a prospective study and related this to their shoe size. The median stretched penile length for the sampled population was 13 cm and the median UK shoe size was 9 (European 43). There was no statistically significant correlation between shoe size and stretched penile length. BJU Int. 2002 Oct;90(6):586-7 *A 2005 Study, "Penile measurements in normal adult Jordanians and in patients with erectile dysfunction." The purpose of this work was to determine penile size in adult normal (group one, 271) and impotent (group two, 109). In group one mean midshaft circumference was 89.8±14 cm, mean flaccid length was mean 9.3±19 cm, and mean stretched length was 13.5±23 cm. In group two, mean flaccid length was 7.7±13 cm, and mean stretched length was 11.6±14 cm.Int J Impot Res. 2005 Mar-Apr;17(2):191-5 *A test-retest study was done in 2002. The study aimed to establish the test-retest reliability of measurement of the erect penis using paper strips in a sample of 312 gay men. The men were issued with color-coded measuring strips printed with instructions but no calibrations, and asked to measure both the length and circumference of their partners' erect penis. Three months later they were asked to repeat these measures. Mean length on first measurement was 15.3 cm and 15.2 cm on second measurement. Mean girth at first measurement was 12.5 cm and 12.6 cm at second measurement. Test-retest reliability of measurement was found to be moderately low at r = 0.60 for length and r = 0.53 for girth" 1: Arch Sex Behav. 2002 Aug;31(4):351-7.
The following are two non-scientificself-measurement reports, and as noted above, claims are typically inaccurate. *According to the Definitive Penis Size Survey, the "mean length of the erect penis according to racial background" reported 16.4 cm (6.5 in) for Caucasian men, 15.5 cm (6.1 in) for Black men, 14.9 cm (5.9 in) for Hispanic men, and 14.0 cm (5.5) in for East Asian men. "The average flaccid length among Blacks however was 9.38 cm (3.7 in) compared to 8.77 cm (3.4 in) for Caucasians." *Another self-measurement survey done by JackinWorld found: "Average approximate penis size based on ethnicity (age 16 and over):" African/black: 17.2 cm (6.74 inches) Native American: 16.5 cm (6.49 inches) Middle Eastern: 16.0 cm (6.28 inches) European/white: 15.9 cm (6.26 inches) Hispanic: 15.3 cm (6.03 in) Asian/Pacific Islander: 14.0 cm (5.50 inches). The survey had total responses of European/white: 80.9% (4045) Asian/Pacific Islander: 8.1% (405) Hispanic: 4.1% (205) Other: 2.7% (135) African/black: 2.6% (130) Native American: 0.8% (40) Middle Eastern: 0.7% (28)
There are many theories as to why there is a differentiation in the average penis size for race. The most obvious would be genetics while some may link penis size to culture; specifically to diet.
Penis size and condom use
In a British study examining condom use and reproductive health, the authors stated that "penis size could affect condom failure." The cross-sectional study looked at race factors on condom use. In this study, 18% of people of African descent, 7% of Caucasians and no Asians reported frequent breakage. In contrast, 21% of Asians, 8% of blacks and 2% of whites reported frequent complete slippage. Tovey SJ, Bonell CP. Condoms: a wider range needed. (letter) BMJ 1993;307:987. Cited in [6]
Based on the hypothesis that anatomical differences exist among regions, a series of FHI studies were conducted in three Asian countries to compare small and standard width condoms (3.9 cm and 4.9 cm), and in three African countries to compare larger and standard width condoms (5.5 cm and 5.2 cm).
According to FHI, "Among the African sites, breakage rates were slightly higher and slippage was slightly lower for the smaller of the two condoms being compared." Joanis C, Brookshire T, Piedrahita C, et al. Evaluation of Two Condom Designs: A Comparison of Standard and Larger Condoms in Ghana, Kenya, and Mali. Durham, NC: Family Health International, 1990. Cited in [7] The data from the Asian sites was inconsistent. Neupane S, Abeywickrema D, Martinez K, et al. Acceptability and Actual Use Breakage and Slippage Rates of Standard and Smaller Latex Condoms: Nepal and Sri Lanka. Durham, NC: Family Health International, 1992. Cited in [8]Andrada A, Ravelo N, Spruyt A, et al. Acceptability and Functionality of Standard and Smaller Latex Condoms during Human Use: Philippines. Durham, NC: Family Health International, 1993. Cited in [9]
FHI concluded that "almost none of the differences in breakage and slippage rates from either the Asian or African sites were statistically significant. Thus, results from these studies pertaining to penis size and condom failure were inconclusive."[10]
* 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 Behavior28:213-221.(PMID:10410197)[11] *Mortlock DP, Innis JW (1997) Mutation of HOXA13 in hand-foot-genital syndrome.Nat Genet15(2):179-80.(PMID:9020844)[12] *Goodman FR (2002) Limb malformations and the human HOX genes. Am J Med Genet112(3):256-265(PMID:12357469)[13] *Shah, J. & Christopher, N. (2002) Can Shoe Size Predict Penile Length? BJU Int90(6):586-7 (PMID:12230622)[14] *Siminoski K and Bain J (1993) The Relationship Among Height, Penile Length, and Foot Size. Annals of Sex Research6(3):231-235 *Kondo T, Zakany J, Innis JW, Duboule D.(1997) Of fingers, toes and penises. Nature390(6655):29(PMID:9363887)[15] *Rushton, J.P. & Bogaert, A.F. (1987) Race differences in sexual behavior: Testing an evolutionary hypothesis. Journal Research in Personality 21(4): pp. 536-7 *Eisenman, Russell (2001) "Penis size: Survey of female perceptions of sexual satisfaction", PubMed Central (PMC)
