Human penis size varies on a number of measures, includinglength andcircumference whenflaccid anderect. Besides the natural variability ofhuman penises in general, there are factors that lead to minor variations in a particular male, such as the level ofarousal, time of day, ambient temperature,anxiety level, physical activity, and frequency of sexual activity. Compared to otherprimates, including large examples such as the gorilla, the human penis is thickest, both in absolute terms and relative to the rest of the body. 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 ofpuberty and, at the latest, approximately 17 years of age.[1]
Measurements vary, with studies that rely on self-measurement reporting a significantly higher average than those with a health professional measuring. A 2015systematic review measured by health professionals rather than self-reporting, found an average erect length of 13.12 cm (5.17 in), and average erect circumference of 11.66 cm (4.59 in).[2] A 1996 study of flaccid length found a mean of 8.8 cm (3.5 in) when measured by staff.[3] Flaccid penis length can sometimes be a poor predictor of erect length. An adult penis that is abnormally small but otherwise normally formed is referred to in medicine as amicropenis.
Limited to no statistically significant correlation between penis size and the size of other body parts has been found in research. Some environmental factors in addition to genetics, such as the presence ofendocrine disruptors, can affect penis growth.
While results vary slightly across reputable studies, the consensus is that themean human penis, when erect, is in the range 5–6 in (13–15 cm) in length.[3][4][5]
The 2015review (measured by staff) found average flaccid, stretched, and erect lengths of 9.16 cm (3.61 in), 13.24 cm (5.21 in), and 13.12 cm (5.17 in), respectively, and average flaccid and erect circumferences of 9.31 cm (3.67 in) and 11.66 cm (4.59 in), respectively. Erect length in the studies was measured by pushing the pre-pubic fat pad to the bone, and flaccid or erect girth (circumference) was measured at the base or mid-shaft of the penis.[2]
A review of studies found average flaccid length to be 9–10 cm (3.5–3.9 in).[6] Length of the flaccid penis does not necessarily correspond to length of the erect penis; some smaller flaccid penises grow much longer, while some larger flaccid penises grow comparatively less.[7]
The penis and scrotum can contract involuntarily in reaction to cold temperatures, anxious or nervous level and participation in sports.[8] This decrease of flaccid penis size is referred to by the slang term "shrinkage", due to action by thecremaster muscle. The same phenomenon affects cyclists and exercise bike users, with prolonged pressure on theperineum from thebicycle saddle and the straining of the exercise causing the penis and scrotum to contract involuntarily. An incorrect saddle may ultimately causeerectile dysfunction (seecrotch pressure for more information). Individuals withhard flaccid syndrome or otherpelvic floor disorders may temporarily have an abnormally small penis.
Neither age or size of the flaccid penis accurately predicted erectile length. Stretched length has correlated with erect length in some cases.[3] However, studies have also shown drastic differences between stretched and erect length.[9] One study found that a minimal tension force of approximately 450 g during stretching of the penis was required to reach a full potential erection length. This study also found that tension forces exerted in this study by the urologist were shown to be significantly (P<0.01) lower than 450g.[10] This may account for differences between stretched and erect length.
Scientific studies have been performed on theerect length of the adult penis. Studies that have relied on self-measurement, including from Internet surveys, consistently reported a higher average length than those that used medical or scientific methods to obtain measurements.[5][13]
A 2020 review found most men believed the average erect penis length is more than 15.24 cm (6 inches). This inaccurate belief has likely been fed by inaccurate and exaggerated data presented in studies where the size of a participant's erect penis is self-reported. Participants may report overestimates of the size of their penis in the belief that a larger penis is more socially desirable.[14] The same review analyzed the results from ten prior studies where measurements of erect penis size were made by researchers. They reported an erect penis to be between 12.95 and 13.92 cm (5.1 and 5.5 inches, respectively) in length, a result significantly below the average obtained in self-reported studies. The authors commented that results of such measurement studies may still be inflated due tovolunteer bias — the possibility that men with larger penises may be more likely to choose to participate in such studies.[14]
Similar results exist regarding studies of thecircumference of the adult fullyerect penis, with the measurement usually taken mid-shaft.[6] As with length, studies that relied on self-measurement consistently reported a significantly higher average than those with staff measuring. In a study of penis size where measurements were taken in a laboratory setting, the average penis circumference when erect was 11.66 cm (4.59 inches).[2]
The average stretched penile length at birth is about 4 cm (1.6 in), and the length for 90% of newborn boys is 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 ofpuberty.[1][6]The average size at the beginning of puberty is 6 cm (2.4 in), with adult size reached about 5 years later.
W.A. Schonfeld published a penis growth curve in 1943.[15][needs update]
Age is not believed to negatively correlate with penis size.[6]
Height is correlated with flaccid stretched length and erect length.[2]
A study investigating the relationship withdigit ratio and found men with longer ring fingers than index fingers had slightly longer penises.[16][17] However, thecommon misconception that hand size predicts penis size has been widely discredited.[18][19]
There is no correlation betweenshoe size and stretched penis size.[20][21]
Nose size was highly related to stretched penile length in Japanese male cadavers.[22]
There may be a link between the malformation of the genitalia and the human limbs. The development of the penis in an embryo is controlled by some of the sameHox genes (in particularHOXA13 andHOXD13)[23] as those that control the development of the limbs. Mutations of some Hox genes that control the growth of limbs cause malformed genitalia (hand-foot-genital syndrome).[24]
Alleged differences in races have led to the creation ofsexual myths. There is no scientific background to support the alleged 'oversized' penis in black people.[25] There is no indication that penis size differs between enthnicities.[2]
According tourologist Aaron Spitz, many websites and studies promoting variation of penis size between races useunscientific methods of collecting information and often ignore contradictory evidence. He concludes that "when you really take a good look at the naked data, there's not a whole lot there [showing racial variation in penis size]."[26]
In a 1994 cover story byPsychology Today,[27][28] 1,500 readers (about two-thirds women) were surveyed about male body image. Many of the women were not particularly concerned with penis size, and over 71% thought men overemphasized the importance of penis size and shape. Generally, the women polled cared more about width than men thought, and less about length than men thought, although the strength of caring for either among women showed a similar pattern.
A small study of 50 undergraduate women, surveyed by two popular male athletes on campus about their perceptions of sexual satisfaction; found the width of a penis feels better than the length of a penis, when subjects are asked to choose between the two (size was left unspecified). It was also concluded that this may show that penis size overall affects sexual satisfaction, since women chose between the two options they were given.[29]
A 2002 study atGroningen University Hospital, asked 375 sexually active women (who had recently given birth) the importance of penis size. The results showed that 21% of women felt length was important and 32% felt that girth was important.[30]
A 2013 study conducted at theAustralian National University, showed that penis size influences a man's sex appeal, and the taller the man, the bigger the effect.[31] The study showed life-sized 3D computer-generated images, altering the height and other physical attributes, with women typically registering preferences in under 3 seconds. A preference for taller men's larger penis size was indicated.
A 2015 US study of the stated preferences of 75 women using3D-printed models as references showed a preferred penis length of 16 cm (6.3 in) and a preferred circumference of 12.2 cm (4.8 in) for long-term sexual partners, with slightly larger preferred sizes of a length of 16.3 cm (6.4 in) and circumference of 12.7 cm (5.0 in) for one-time sexual encounters.[32]
According to the study, however, when estimating the length of their partner's penis, most women would say a size significantly smaller than what their partner was recorded to be. This suggests that perception of size is not entirely accurate.[32] The visual impression of the size is not necessarily in correlation with the feeling in the vulva and vagina. A very long penis can causedyspareunia, if the man doesn't understand how to use it carefully.
One Australian study of 184 men looked at penis length and circumference in relation to condom breakage or slippage. 3,658 condoms were used. The study found that when used correctly, condoms had a breakage rate of 1.34% and a slippage rate of 2.05%, for a total failure rate of 3.39%. Penile dimensions did not influence slippage, although penis circumference and broken condoms were strongly correlated, with larger sizes increasing the rate of breakage.[33]
Androgens liketestosterone are responsible for penis enlargement and elongation during puberty.[34] Penis size is positively correlated with increasing testosterone levels during puberty.[35] But after puberty, administration of testosterone does not affect penis size, and androgen deficiency in adult men only results in a small decrease in size.[35]Growth hormone (GH) andinsulin-like growth factor 1 (IGF-1) are also involved in penis size, with deficiency (such as that observed ingrowth hormone deficiency orLaron syndrome) at critical developmental stages having the potential to result inmicropenis.[36]
There are certain genes, likehomeobox (Hox A and D) genes, which may have a role in regulating penis size. In humans, theAR gene, located on theX chromosome at Xq11-12, may affect penis size. TheSRY gene located on theY chromosome may have a role to play. Variance in size can often be attributed tode novo mutations. Deficiency ofpituitary growth hormone orgonadotropins or mild degrees of androgen insensitivity can cause small penis size in males and can be addressed with growth hormone or testosterone treatment in early childhood.[citation needed]
An adult penis with an erect length of 2.5SD below the average but otherwise formed normally is referred to in a medical context as having themicropenis condition.[37] The condition affects 0.6% of men.[7] Some of the identifiable causes aredeficiency of pituitary growth hormone orgonadotropins, mild degrees ofandrogen insensitivity, a variety of genetic syndromes and variations in certainhomeobox genes. Some types of micropenis can be addressed with growth hormone ortestosterone treatment in early childhood. Operations are also available to increase penis size in cases of micropenis in adults.[38]
It has been suggested that differences in penis size between individuals are caused not only bygenetics, but also by environmental factors such asculture,diet and chemical or pollution exposure.[39][40][41][42]Endocrine disruption resulting from chemical exposure has been linked to genital deformation in both sexes (among many other problems). Chemicals from both synthetic (e.g., pesticides, anti-bacterialtriclosan,plasticizers for plastics) and natural (e.g., chemicals found intea tree oil and lavender oil)[43][44] sources have been linked to various degrees of endocrine disruption.
BothPCBs and the plasticizerDEHP have been associated with smaller penis size.[45] DEHP metabolites measured from the urine of pregnant women have been significantly associated with the decreased penis width, shorteranogenital distance and the incomplete descent oftesticles of their newborn sons, replicating effects identified in animals.[46] According to a 2008 study published by the USNational Library of Medicine, approximately 25% of US women havephthalate levels similar to those observed in animals.[46]
Penile size may decrease as a result of somehormonal therapy combined with external beamradiation therapy.[47] In addition, some estrogen-basedfertility drugs likediethylstilbestrol (DES) have been linked to genital abnormalities or a smaller than normal penis (microphallus).[48]
Perceptions of penis size are culture-specific.[49] Some prehistoric sculptures andpetroglyphs depict male figures with exaggerated erect penises.[50]Ancient Egyptian cultural and artistic conventions generally prevented large penises from being shown in art, as they were considered obscene,[51] but the scruffy, balding male figures in theTurin Erotic Papyrus are shown with exaggeratedly large genitals.[51][52] The Egyptian godGeb is sometimes shown with a massive erect penis and the godMin is almost always shown with an erection.[50]
The males ofancient Greece believed that small penises were ideal.[49] Scholars believe that most ancient Greeks probably had roughly the same size penises as most other Europeans,[49] but Greek artistic portrayals of handsome youths show them with inordinately small, uncircumcised penises with disproportionately largeforeskins,[49] indicating that these were seen as ideal.[49] Large penises inGreek art are reserved exclusively for comically grotesque figures,[49][50] such assatyrs, a class of hideous, horse-like woodland spirits, who are shown in Greek art with absurdly massive penises.[49]Actors portraying male characters inancient Greek comedy wore enormous, fake, red penises, which dangled underneath their costumes;[54]
InAristophanes's comedyThe Clouds, "Mr. Good Reason" gives the character Pheidippides a description of the ideal youth: "A glistening chest and glowing skin / Broad shoulders, a small tongue /A mighty bottom and a tiny prong."[55]InGreek mythology,Priapus, the god of fertility, had an impossibly large penis that was alwayspermanently erect.[56][50] Priapus was widely seen as hideous and unattractive.[56] Ascholion onApollonius of Rhodes'sArgonautica states that, when Priapus's motherAphrodite, the goddess of love and beauty, gave birth to him, she was so horrified by the size of his penis, his massivepotbelly, and his huge tongue that sheabandoned him to die in the wilderness.[56] A herdsman found him and raised him as his son,[56] later discovering that Priapus could use his massive penis to aid in the growth of plants.[56]
Nonetheless, there are indications that the Greeks had an open mind about large penises.[50] A statue of the godHermes with an exaggerated penis stood outside the main gate ofAthens[50] and inAlexandria in 275 BC, a procession in honor ofDionysus hauled a 180-foot phallus through the city and people venerated it by singing hymns and reciting poems.[50] The Romans, in contrast to the Greeks, seem to have admired large penises[50][53] and large numbers of large phalli have been recovered from the ruins ofPompeii.[50] Depictions of Priapus were very popular in Roman erotic art and literature.[50][53] Overeighty obscene poems dedicated to him have survived.[50]
Penis size is alluded to in theBible:[50]
18 And she revealed her whorings, and she revealed her nakedness, and so I turned from herjust as I turned from her sister.19 Yet she increased her whorings,recalling the days of her childhood when she was prostituted in the land of Egypt.20 And she lusted after her male lovers whose genitaliawere the genitalia of male donkeys andtheir seminal emissionwas the seminal emission of horses.Ezekiel 23:18–20 Lexham English Bible
Ancient Chinese legend holds that a man namedLao Ai had the largest penis in history and that he had an affair withQueen Dowager Zhao (c. 280–228 BC), the mother ofQin Shi Huang, by pretending to be aeunuch.[50]Ancient Koreans admired large penises andKing Jijeung (437–514 AD) of theSilla Dynasty is said to have had a forty-five-centimeter penis that was so large his subordinates had to search for a woman that fit him.[50] TraditionalJapanese erotic paintings usually show genitals as exaggeratedly large.[50] The oldest known painting of this type, found in theHōryū-ji Temple inIkaruga, dates to the eighth century AD and depicts a fairly large penis.[50]
The ancient Indian sexual treatiseKama Sutra, originally written inSanskrit, probably between the second and fourth centuries AD, divides men into three classes based on penis size: "hare" size (about 5–7 cm, or 2–3 inches, when erect), "bull" size (10–15 cm, or 4–6 inches), and "horse" size (18–20 cm, or 7–8 inches).[50] The treatise also divides women's vaginas into three sizes ("deer", "mare", and "elephant")[50] and advises that a man match the size of the vagina of the woman he is having sex with to the size of his own penis.[50] It also gives medically dubious advice on how to enlarge one's penis usingwasp stings.[50]
In medievalArabic literature, a longer penis was preferred, as described in anArabian Nights tale called "Ali with the Large Member". As a wittysatire of this fantasy, the 9th-centuryAfro-Arab authorAl-Jahiz wrote: "If the length of the penis were a sign of honor, then themule would belong to theQuraysh" (the tribe to whichMuhammad belonged and from which he descended).[57][50]
The medievalNorsemen considered the size of a man's penis as the measure of his manliness,[58] and a thirteenth-century Norse magictalisman fromBergen, awooden stave inscribed with writing inrunic script, promises its wearer: "You will fuck Rannveig the Red. It will be bigger than a man's prick and smaller than a horse's prick."[58] A late fourteenth century account of the life ofSaint Óláfr from theFlateyjarbók describes a pagan ritual which centered around a preserved horse's penis used as a cult artifact[58] which members of the cult would pass around in a circle,[58] making up verses in praise of it,[58] encouraging it and the other members of the group to behave in sexually suggestive ways.[58]
During theRenaissance, some men in Europe began to wearcodpieces, which accentuated their genitals.[50] There is no direct evidence that it was necessarily worn to enhance the apparent size of the wearer's penis,[50] but larger codpieces were seen as more fashionable.[50]
Males may quite easily underestimate the size of their own penis relative to those of others. A survey bysexologists showed that many men who believed that their penis was of inadequate size had average-sized penises.[59] Another study found sex education of standard penile measurements to be helpful and relieving for patients concerned about small penis size, most of whom had incorrect beliefs of what is considered medically normal.[60] The study found that almost all of their patients that were concerned about their penis size overestimated the average penis size. The perception of having a large penis is often linked to higher self-esteem.[61] Fears of shrinking of the penis in folklore have led to a type ofmass hysteria calledpenis panic, though the penis legitimately can shrink in size due to scar tissue formation in the penis from a medical condition calledPeyronie's disease.[62][63] Marketers ofpenis enlargement products exploit fears of inadequacy, but there is no consensus in the scientific community of any non-surgical technique that permanently increases either the thickness or length of the erect penis that already falls into the normal range.
Small penis syndrome (SPS), a term sometimes used in medical literature, is characterized by an obsessive concern that the penis is smaller than average, often despite normal measurements. It has been associated with wider psychological disorders, includinganxiety and bodydysmorphic disorder. Assessment focuses on confirming normality and addressing underlying psychological factors.[64][65]
Widespread private concerns related to penis size have led to a number offolklore sayings andpopular culture reflections related to penis size. Penis panic is a form of mass hysteria involving the believed removal or shrinking of the penis, known asgenital retraction syndrome. The penis can significantly shrink due to scar tissue formation from a condition called Peyronie's disease which affects up to 10% of men.[66] Products such as penis pumps, pills, and other dubious means of penis enlargement are some of the most marketed products inemail spam. At present there is no consensus in the scientific community of any non-surgical technique that permanently increases either the thickness or length of the erect penis that already falls into the normal range (4.5" to 7").
A study undertaken atUtrecht University found that the majority ofgay men in the study regarded a large penis as ideal, and having one was linked to self-esteem.[67] One study analysing the self-reportedKinsey data set found that the average penis of a homosexual man was larger than the average penis of their heterosexual counterparts (6.32 inches [16.05 cm] in length amongst gay men versus 5.99 in [15.21 cm] in heterosexuals, and 4.95 inches [12.57 cm] circumference amongst gay men versus 4.80 in [12.19 cm] in heterosexual men).[68]
While more than 46% of people have watchedpornography, with 30%–90% of women and 60%–98% of men having watched it at some point in their lifespan, between 1973 and 2016, among and in comparison to other racial groups,Black women and Black men were reported to have watched the most porn.[69] Pornography tends to depictBlack people throughracist andsexiststereotypes, such as Black people being hypersexual and animalistic, andsexually objectifies Black people through its emphasis and focus on sexual vigor and genitalia; this is socially generated and reinforced through production and supply of porn, such asBlack porn andinterracial porn that initially debuted in 1982 and big Black cock (BBC) porn, which then meets the demand from porn consumers, such as White men withfantasies about thesexuality of Black people in 1982 and porn consumers onPornhub whose top search terms in 2022 were: "Black", the 13th most searched term, "BBC", the 9th most searched term, and "Ebony", the 3rd most searched term and the most searched category of 2022.[69] Cosmetic changes and digital changes to genitalia can occur in porn, with theLabia minora of women being portrayed as smaller than the average size and the penis of men being portrayed as larger than the average size.[69] Genital self-image is affected by the consumption of pornography as the primary focus of pornography is on genitalia andsexual acts.[69] The genitalself-image and focus for Black women were genital odor and appearance, and the genital self-image and focus for Black men were penis size; racially diverse study sample sizes indicate that, in contrast to women who tend to have a less positive genital self-image, men tend to have a more positive genital self-image.[69]
The human penis is thicker than that of any other primate, both in absolute terms and relative to the rest of the body.[70] Early research, based on inaccurate measurements, concluded that the human penis was also longer. In fact, the penis of thecommon chimpanzee is no shorter than in humans, averaging 14.4 cm (5.7 inches), and some other primates have comparable penis sizes relative to their body weight.[71]
The evolutionary reasons for the increased thickness have not been established.[72][needs update] One explanation is that thicker penises are anadaptation to a corresponding increase invaginal size. The vaginal canal is believed to have expanded in humans to accommodate the larger size of a newborn'sskull. Women may then havesexually selected men with penises large enough to fit their vagina, to providesexual stimulation and ensureejaculation.[72]
Other evolutionary hypotheses to explain humans' relatively large penis length and girth include a sperm competition hypothesis and a mate competition hypothesis. The sperm competition hypothesis does not have much support as in other mammals where sperm competition is present, larger testes evolve, not larger penises. The mate competition hypothesis involves the prediction that a human with a larger penis would be able to displace the sperm of another. Studies have found that larger penises do not displace other sperm more effectively than smaller penises, but rather longer penises may ejaculate sperm inside the vagina in places that would be harder for a following penis to displace. The depth of pelvic thrusting was correlated to the displacement of competing sperm.[73]
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