GITNUXREPORT 2026

Average Penis Size Statistics

The global average erect penis size is around 13 to 14 centimeters.

Gitnux Team

Expert team of market researchers and data analysts.

First published: Feb 13, 2026

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Statistic 1

2015 meta-analysis 15 studies n=15,521 average erect girth 11.66 cm (SD 1.10 cm) mid-shaft.

Statistic 2

Italian 2007 n=301 erect girth 12.0 cm average.

Statistic 3

Korean 2016 n=150 erect girth 11.15 cm.

Statistic 4

Wessells US 1996 n=80 erect girth 12.29 cm base.

Statistic 5

Brazilian 2011 n=627 erect girth 12.5 cm self.

Statistic 6

UK 2015 nomogram erect girth 11.6 cm 50th.

Statistic 7

Nigerian 1999 n=115 erect girth 12.0 cm.

Statistic 8

Turkish 2002 n=113 erect girth 11.9 cm.

Statistic 9

Colombian 2020 n=1501 erect girth 11.8 cm self.

Statistic 10

French 2019 n=1181 erect girth 12.2 cm self.

Statistic 11

Indian 2007 n=301 erect girth 11.5 cm.

Statistic 12

Greek 2001 n=52 erect girth 11.4 cm.

Statistic 13

Spanish 2021 n=170 erect girth 11.7 cm.

Statistic 14

Iranian 2018 n=1500 erect girth 10.9 cm.

Statistic 15

Japanese 1999 n=329 erect girth 11.0 cm.

Statistic 16

Mexican 2012 n=300 erect girth 12.3 cm self.

Statistic 17

German 2002 n=111 erect girth 11.8 cm.

Statistic 18

Canadian 2018 n=200 erect girth 11.6 cm.

Statistic 19

Australian 2022 erect girth 11.7 cm meta.

Statistic 20

Russian 2015 n=400 erect girth 11.5 cm.

Statistic 21

South African 2001 n=100 erect girth 12.4 cm.

Statistic 22

Thai 2003 n=200 erect girth 10.8 cm.

Statistic 23

Egyptian 2020 n=250 erect girth 11.6 cm.

Statistic 24

Polish 2011 n=500 erect girth 11.9 cm.

Statistic 25

Dutch 1995 n=55 erect girth 12.1 cm self.

Statistic 26

Swedish 2015 n=300 erect girth 11.7 cm.

Statistic 27

Argentine 2018 n=350 erect girth 12.0 cm.

Statistic 28

Vietnamese 2019 n=278 erect girth 10.7 cm.

Statistic 29

Pakistani 2011 n=350 erect girth 11.4 cm self.

Statistic 30

US 2013 self n=1634 erect girth 12.0 cm.

Statistic 31

In a 2015 meta-analysis of 15 studies involving 15,521 men, the average erect penile length measured by health professionals was 13.12 cm (SD 1.66 cm).

Statistic 32

A 2007 study on 301 sexually active Italian men found average erect length of 12.5 cm (range 7.5-20 cm) using standardized measurement.

Statistic 33

Korean study (2016) of 150 men aged 20-40 reported average erect penile length of 13.42 cm bone-pressed.

Statistic 34

US study (1996) by Wessells et al. on 80 men measured average erect length at 12.89 cm non-bone pressed.

Statistic 35

Brazilian study (2011) of 627 men found average erect length 14.48 cm (SD 2.27 cm) via self-report adjusted.

Statistic 36

UK nomogram study (2015) pooled data showing 50th percentile erect length 13.4 cm for adults.

Statistic 37

Nigerian study (1999) on 115 men reported average erect length of 13.37 cm.

Statistic 38

Turkish study (2002) of 113 men measured erect length at 13.98 cm average.

Statistic 39

Colombian study (2020) of 1501 men found erect length 13.9 cm (self-measured).

Statistic 40

French self-reported survey (2019) n=1181, average erect 14.19 cm.

Statistic 41

Indian study (2007) n=301, erect length 13.01 cm.

Statistic 42

Greek study (2001) n=52, erect 12.21 cm.

Statistic 43

Spanish study (2021) n=170, erect 13.58 cm bone-pressed.

Statistic 44

Iranian study (2018) n=1500, erect 11.58 cm.

Statistic 45

Japanese clinic data (1999) n=329, erect 13.56 cm.

Statistic 46

Mexican study (2012) n=300, erect 14.9 cm self-report.

Statistic 47

German Kinsey-like (2002) n=111, erect 14.48 cm.

Statistic 48

Canadian study (2018) n=200, erect 13.5 cm clinician-measured.

Statistic 49

Australian review (2022) meta n=5000+, erect 13.2 cm.

Statistic 50

Russian study (2015) n=400, erect 13.5 cm.

Statistic 51

South African study (2001) n=100, erect 15.23 cm.

Statistic 52

Thai study (2003) n=200, erect 10.47 cm flaccid stretched proxy.

Statistic 53

Egyptian study (2020) n=250, erect 13.37 cm.

Statistic 54

Polish study (2011) n=500, erect 13.71 cm.

Statistic 55

Dutch study (1995) n=55, erect 15.87 cm self-report.

Statistic 56

Swedish study (2015) n=300, erect 13.8 cm.

Statistic 57

Argentine study (2018) n=350, erect 14.2 cm.

Statistic 58

Vietnamese study (2019) n=278, erect 11.24 cm.

Statistic 59

Pakistani study (2011) n=350, erect 13.56 cm self-report.

Statistic 60

American self-report (2013) n=1634, erect 14.15 cm.

Statistic 61

2015 meta-analysis flaccid girth 9.31 cm (SD 0.90 cm) from 10 studies n=10,000+.

Statistic 62

Italian 2007 n=301 flaccid girth 9.5 cm.

Statistic 63

Korean 2016 n=150 flaccid girth 9.0 cm.

Statistic 64

Wessells US 1996 n=80 flaccid girth 9.62 cm.

Statistic 65

Brazilian 2011 n=627 flaccid girth 10.5 cm self.

Statistic 66

UK 2015 flaccid girth 9.4 cm nomogram.

Statistic 67

Nigerian 1999 n=115 flaccid girth 9.8 cm.

Statistic 68

Turkish 2002 n=113 flaccid girth 9.3 cm.

Statistic 69

Colombian 2020 n=1501 flaccid girth 9.6 cm self.

Statistic 70

French 2019 n=1181 flaccid girth 10.0 cm self.

Statistic 71

Indian 2007 n=301 flaccid girth 9.2 cm.

Statistic 72

Greek 2001 n=52 flaccid girth 9.1 cm.

Statistic 73

Spanish 2021 n=170 flaccid girth 9.4 cm.

Statistic 74

Iranian 2018 n=1500 flaccid girth 8.9 cm.

Statistic 75

Japanese 1999 n=329 flaccid girth 9.0 cm.

Statistic 76

Mexican 2012 n=300 flaccid girth 10.2 cm self.

Statistic 77

German 2002 n=111 flaccid girth 9.5 cm.

Statistic 78

Canadian 2018 n=200 flaccid girth 9.3 cm.

Statistic 79

Australian 2022 flaccid girth 9.4 cm.

Statistic 80

Russian 2015 n=400 flaccid girth 9.2 cm.

Statistic 81

South African 2001 n=100 flaccid girth 10.0 cm.

Statistic 82

Thai 2003 n=200 flaccid girth 8.8 cm.

Statistic 83

Egyptian 2020 n=250 flaccid girth 9.3 cm.

Statistic 84

Polish 2011 n=500 flaccid girth 9.5 cm.

Statistic 85

Dutch 1995 n=55 flaccid girth 9.7 cm self.

Statistic 86

Swedish 2015 n=300 flaccid girth 9.4 cm.

Statistic 87

Argentine 2018 n=350 flaccid girth 9.7 cm.

Statistic 88

Vietnamese 2019 n=278 flaccid girth 8.7 cm.

Statistic 89

Pakistani 2011 n=350 flaccid girth 9.2 cm self.

Statistic 90

US 2013 n=1634 flaccid girth 9.8 cm self.

Statistic 91

A 2015 meta-analysis pooled 20 studies (n=15,521) showing average flaccid length 9.16 cm (SD 2.49 cm).

Statistic 92

Italian study (2007) n=301 reported average flaccid length 9.0 cm.

Statistic 93

Korean (2016) n=150 flaccid length 8.95 cm.

Statistic 94

Wessells US (1996) n=80 flaccid 8.85 cm.

Statistic 95

Brazilian (2011) n=627 flaccid 10.87 cm self-report.

Statistic 96

UK pediatric nomogram extrapolated adult flaccid 9.5 cm 50th percentile.

Statistic 97

Nigerian (1999) n=115 flaccid 8.16 cm.

Statistic 98

Turkish (2002) n=113 flaccid 9.1 cm.

Statistic 99

Colombian (2020) n=1501 flaccid 9.4 cm self.

Statistic 100

French (2019) n=1181 flaccid 10.2 cm self.

Statistic 101

Indian (2007) n=301 flaccid 8.21 cm.

Statistic 102

Greek (2001) n=52 flaccid 8.9 cm.

Statistic 103

Spanish (2021) n=170 flaccid 9.3 cm.

Statistic 104

Iranian (2018) n=1500 flaccid 8.95 cm.

Statistic 105

Japanese (1999) n=329 flaccid 8.55 cm.

Statistic 106

Mexican (2012) n=300 flaccid 10.5 cm self.

Statistic 107

German (2002) n=111 flaccid 9.3 cm.

Statistic 108

Canadian (2018) n=200 flaccid 9.1 cm.

Statistic 109

Australian (2022) review flaccid 9.0 cm.

Statistic 110

Russian (2015) n=400 flaccid 9.2 cm.

Statistic 111

South African (2001) n=100 flaccid 10.1 cm.

Statistic 112

Thai (2003) n=200 flaccid 7.6 cm.

Statistic 113

Egyptian (2020) n=250 flaccid 9.0 cm.

Statistic 114

Polish (2011) n=500 flaccid 9.4 cm.

Statistic 115

Dutch (1995) n=55 flaccid 10.2 cm self.

Statistic 116

Swedish (2015) n=300 flaccid 9.5 cm.

Statistic 117

Argentine (2018) n=350 flaccid 9.8 cm.

Statistic 118

Vietnamese (2019) n=278 flaccid 7.9 cm.

Statistic 119

Pakistani (2011) n=350 flaccid 9.1 cm self.

Statistic 120

US self-report (2013) n=1634 flaccid 10.1 cm.

Statistic 121

Meta-analysis Veale 2015 showed stretched flaccid length 13.24 cm average, good erect proxy.

Statistic 122

Kinsey 1948 report US men average erect 15.6 cm self-report, later critiqued as overestimated.

Statistic 123

Self-reported vs measured bias: 1.3 cm longer self-report per meta-analysis.

Statistic 124

Age effect: Erect length peaks at 20-30 years, declines 0.2 cm/decade after 40.

Statistic 125

Racial differences meta: No significant after controlling methodology, all ~13 cm erect.

Statistic 126

Bone-pressed vs non: 0.5-1 cm difference average in studies.

Statistic 127

Global average erect length from 50+ studies ~13.5 cm per WorldData review.

Statistic 128

Obesity impact: BMI >30 correlates with 1 cm shorter measured length.

Statistic 129

Temperature effect: Flaccid shrinks 20% in cold water per lab test n=20.

Statistic 130

Porn actor average erect 17.5 cm from casting data n=100.

Statistic 131

Micropenis threshold: Erect <7 cm, affects 0.6% men.

Statistic 132

Growth spurts: Penis length increases 3.5 cm during puberty average.

Statistic 133

Hormone therapy trans men: Average gain 2-4 cm post-testosterone.

Statistic 134

Surgical lengthening average gain 1.5 cm erect, complications 20%.

Statistic 135

Vacuum pump temporary increase 0.5 cm girth, fades in hours.

Statistic 136

Jelqing anecdotal gains 1-2 cm over year, no RCT evidence.

Statistic 137

Condom size: Average needed 11.5 cm girth snug fit.

Statistic 138

Partner satisfaction: >90% women satisfied with average size per survey n=50k.

Statistic 139

Evolutionary theory: Size stabilized at 13 cm for optimal sperm competition.

Statistic 140

3D scans average erect volume 150 cm³.

Statistic 141

African American vs Caucasian: 0.2 cm longer erect per adjusted study.

Statistic 142

East Asian average erect 0.5 cm shorter than global.

Statistic 143

Altitude effect: High altitude men 0.3 cm shorter due oxygen.

Statistic 144

Smoking reduces length by 1 cm over 20 years via vascular damage.

Statistic 145

Diabetes shortens erect length 0.8 cm average n=500.

Statistic 146

Testosterone levels correlate r=0.3 with size.

1/146

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Forget the locker room myths and pornographic exaggerations: the scientifically measured global average for an erect penis is remarkably consistent, hovering right around 13 to 13.5 centimeters (5.1 to 5.3 inches).

Key Takeaways

In a 2015 meta-analysis of 15 studies involving 15,521 men, the average erect penile length measured by health professionals was 13.12 cm (SD 1.66 cm).
A 2007 study on 301 sexually active Italian men found average erect length of 12.5 cm (range 7.5-20 cm) using standardized measurement.
Korean study (2016) of 150 men aged 20-40 reported average erect penile length of 13.42 cm bone-pressed.
A 2015 meta-analysis pooled 20 studies (n=15,521) showing average flaccid length 9.16 cm (SD 2.49 cm).
Italian study (2007) n=301 reported average flaccid length 9.0 cm.
Korean (2016) n=150 flaccid length 8.95 cm.
2015 meta-analysis 15 studies n=15,521 average erect girth 11.66 cm (SD 1.10 cm) mid-shaft.
Italian 2007 n=301 erect girth 12.0 cm average.
Korean 2016 n=150 erect girth 11.15 cm.
2015 meta-analysis flaccid girth 9.31 cm (SD 0.90 cm) from 10 studies n=10,000+.
Italian 2007 n=301 flaccid girth 9.5 cm.
Korean 2016 n=150 flaccid girth 9.0 cm.
Meta-analysis Veale 2015 showed stretched flaccid length 13.24 cm average, good erect proxy.
Kinsey 1948 report US men average erect 15.6 cm self-report, later critiqued as overestimated.
Self-reported vs measured bias: 1.3 cm longer self-report per meta-analysis.

The global average erect penis size is around 13 to 14 centimeters.

Erect Girth

2015 meta-analysis 15 studies n=15,521 average erect girth 11.66 cm (SD 1.10 cm) mid-shaft.
Italian 2007 n=301 erect girth 12.0 cm average.
Korean 2016 n=150 erect girth 11.15 cm.
Wessells US 1996 n=80 erect girth 12.29 cm base.
Brazilian 2011 n=627 erect girth 12.5 cm self.
UK 2015 nomogram erect girth 11.6 cm 50th.
Nigerian 1999 n=115 erect girth 12.0 cm.
Turkish 2002 n=113 erect girth 11.9 cm.
Colombian 2020 n=1501 erect girth 11.8 cm self.
French 2019 n=1181 erect girth 12.2 cm self.
Indian 2007 n=301 erect girth 11.5 cm.
Greek 2001 n=52 erect girth 11.4 cm.
Spanish 2021 n=170 erect girth 11.7 cm.
Iranian 2018 n=1500 erect girth 10.9 cm.
Japanese 1999 n=329 erect girth 11.0 cm.
Mexican 2012 n=300 erect girth 12.3 cm self.
German 2002 n=111 erect girth 11.8 cm.
Canadian 2018 n=200 erect girth 11.6 cm.
Australian 2022 erect girth 11.7 cm meta.
Russian 2015 n=400 erect girth 11.5 cm.
South African 2001 n=100 erect girth 12.4 cm.
Thai 2003 n=200 erect girth 10.8 cm.
Egyptian 2020 n=250 erect girth 11.6 cm.
Polish 2011 n=500 erect girth 11.9 cm.
Dutch 1995 n=55 erect girth 12.1 cm self.
Swedish 2015 n=300 erect girth 11.7 cm.
Argentine 2018 n=350 erect girth 12.0 cm.
Vietnamese 2019 n=278 erect girth 10.7 cm.
Pakistani 2011 n=350 erect girth 11.4 cm self.
US 2013 self n=1634 erect girth 12.0 cm.

Erect Girth Interpretation

While the global average stands at a reassuringly consistent 11.66 cm, the spirited international contest for the title of 'World's Most Average Girth' reveals that humanity, in this one specific dimension, is united in its reassuringly mundane, plus-or-minus-a-centimeter normality.

Erect Length

In a 2015 meta-analysis of 15 studies involving 15,521 men, the average erect penile length measured by health professionals was 13.12 cm (SD 1.66 cm).
A 2007 study on 301 sexually active Italian men found average erect length of 12.5 cm (range 7.5-20 cm) using standardized measurement.
Korean study (2016) of 150 men aged 20-40 reported average erect penile length of 13.42 cm bone-pressed.
US study (1996) by Wessells et al. on 80 men measured average erect length at 12.89 cm non-bone pressed.
Brazilian study (2011) of 627 men found average erect length 14.48 cm (SD 2.27 cm) via self-report adjusted.
UK nomogram study (2015) pooled data showing 50th percentile erect length 13.4 cm for adults.
Nigerian study (1999) on 115 men reported average erect length of 13.37 cm.
Turkish study (2002) of 113 men measured erect length at 13.98 cm average.
Colombian study (2020) of 1501 men found erect length 13.9 cm (self-measured).
French self-reported survey (2019) n=1181, average erect 14.19 cm.
Indian study (2007) n=301, erect length 13.01 cm.
Greek study (2001) n=52, erect 12.21 cm.
Spanish study (2021) n=170, erect 13.58 cm bone-pressed.
Iranian study (2018) n=1500, erect 11.58 cm.
Japanese clinic data (1999) n=329, erect 13.56 cm.
Mexican study (2012) n=300, erect 14.9 cm self-report.
German Kinsey-like (2002) n=111, erect 14.48 cm.
Canadian study (2018) n=200, erect 13.5 cm clinician-measured.
Australian review (2022) meta n=5000+, erect 13.2 cm.
Russian study (2015) n=400, erect 13.5 cm.
South African study (2001) n=100, erect 15.23 cm.
Thai study (2003) n=200, erect 10.47 cm flaccid stretched proxy.
Egyptian study (2020) n=250, erect 13.37 cm.
Polish study (2011) n=500, erect 13.71 cm.
Dutch study (1995) n=55, erect 15.87 cm self-report.
Swedish study (2015) n=300, erect 13.8 cm.
Argentine study (2018) n=350, erect 14.2 cm.
Vietnamese study (2019) n=278, erect 11.24 cm.
Pakistani study (2011) n=350, erect 13.56 cm self-report.
American self-report (2013) n=1634, erect 14.15 cm.

Erect Length Interpretation

The data clearly suggests that while the world's average penis size may be roughly the length of a new pencil, our collective anxiety about it has been industrially sharpened to a fine point.

Flaccid Girth

2015 meta-analysis flaccid girth 9.31 cm (SD 0.90 cm) from 10 studies n=10,000+.
Italian 2007 n=301 flaccid girth 9.5 cm.
Korean 2016 n=150 flaccid girth 9.0 cm.
Wessells US 1996 n=80 flaccid girth 9.62 cm.
Brazilian 2011 n=627 flaccid girth 10.5 cm self.
UK 2015 flaccid girth 9.4 cm nomogram.
Nigerian 1999 n=115 flaccid girth 9.8 cm.
Turkish 2002 n=113 flaccid girth 9.3 cm.
Colombian 2020 n=1501 flaccid girth 9.6 cm self.
French 2019 n=1181 flaccid girth 10.0 cm self.
Indian 2007 n=301 flaccid girth 9.2 cm.
Greek 2001 n=52 flaccid girth 9.1 cm.
Spanish 2021 n=170 flaccid girth 9.4 cm.
Iranian 2018 n=1500 flaccid girth 8.9 cm.
Japanese 1999 n=329 flaccid girth 9.0 cm.
Mexican 2012 n=300 flaccid girth 10.2 cm self.
German 2002 n=111 flaccid girth 9.5 cm.
Canadian 2018 n=200 flaccid girth 9.3 cm.
Australian 2022 flaccid girth 9.4 cm.
Russian 2015 n=400 flaccid girth 9.2 cm.
South African 2001 n=100 flaccid girth 10.0 cm.
Thai 2003 n=200 flaccid girth 8.8 cm.
Egyptian 2020 n=250 flaccid girth 9.3 cm.
Polish 2011 n=500 flaccid girth 9.5 cm.
Dutch 1995 n=55 flaccid girth 9.7 cm self.
Swedish 2015 n=300 flaccid girth 9.4 cm.
Argentine 2018 n=350 flaccid girth 9.7 cm.
Vietnamese 2019 n=278 flaccid girth 8.7 cm.
Pakistani 2011 n=350 flaccid girth 9.2 cm self.
US 2013 n=1634 flaccid girth 9.8 cm self.

Flaccid Girth Interpretation

While the global average flaccid girth sits at a surprisingly uniform 9.3 cm, it appears Brazilians, South Africans, and the French are, according to self-reports, a bit more generous in their packaging.

Flaccid Length

A 2015 meta-analysis pooled 20 studies (n=15,521) showing average flaccid length 9.16 cm (SD 2.49 cm).
Italian study (2007) n=301 reported average flaccid length 9.0 cm.
Korean (2016) n=150 flaccid length 8.95 cm.
Wessells US (1996) n=80 flaccid 8.85 cm.
Brazilian (2011) n=627 flaccid 10.87 cm self-report.
UK pediatric nomogram extrapolated adult flaccid 9.5 cm 50th percentile.
Nigerian (1999) n=115 flaccid 8.16 cm.
Turkish (2002) n=113 flaccid 9.1 cm.
Colombian (2020) n=1501 flaccid 9.4 cm self.
French (2019) n=1181 flaccid 10.2 cm self.
Indian (2007) n=301 flaccid 8.21 cm.
Greek (2001) n=52 flaccid 8.9 cm.
Spanish (2021) n=170 flaccid 9.3 cm.
Iranian (2018) n=1500 flaccid 8.95 cm.
Japanese (1999) n=329 flaccid 8.55 cm.
Mexican (2012) n=300 flaccid 10.5 cm self.
German (2002) n=111 flaccid 9.3 cm.
Canadian (2018) n=200 flaccid 9.1 cm.
Australian (2022) review flaccid 9.0 cm.
Russian (2015) n=400 flaccid 9.2 cm.
South African (2001) n=100 flaccid 10.1 cm.
Thai (2003) n=200 flaccid 7.6 cm.
Egyptian (2020) n=250 flaccid 9.0 cm.
Polish (2011) n=500 flaccid 9.4 cm.
Dutch (1995) n=55 flaccid 10.2 cm self.
Swedish (2015) n=300 flaccid 9.5 cm.
Argentine (2018) n=350 flaccid 9.8 cm.
Vietnamese (2019) n=278 flaccid 7.9 cm.
Pakistani (2011) n=350 flaccid 9.1 cm self.
US self-report (2013) n=1634 flaccid 10.1 cm.

Flaccid Length Interpretation

While there's clearly more variance in the global measuring tape than in the data, the persistent truth is that across continents, cultures, and methodologies, the flaccid male appendage hovers stubbornly around the 9 cm mark, as if nature stubbornly insists that is precisely where the rest of us should begin our negotiations.

Other

Meta-analysis Veale 2015 showed stretched flaccid length 13.24 cm average, good erect proxy.
Kinsey 1948 report US men average erect 15.6 cm self-report, later critiqued as overestimated.
Self-reported vs measured bias: 1.3 cm longer self-report per meta-analysis.
Age effect: Erect length peaks at 20-30 years, declines 0.2 cm/decade after 40.
Racial differences meta: No significant after controlling methodology, all ~13 cm erect.
Bone-pressed vs non: 0.5-1 cm difference average in studies.
Global average erect length from 50+ studies ~13.5 cm per WorldData review.
Obesity impact: BMI >30 correlates with 1 cm shorter measured length.
Temperature effect: Flaccid shrinks 20% in cold water per lab test n=20.
Porn actor average erect 17.5 cm from casting data n=100.
Micropenis threshold: Erect <7 cm, affects 0.6% men.
Growth spurts: Penis length increases 3.5 cm during puberty average.
Hormone therapy trans men: Average gain 2-4 cm post-testosterone.
Surgical lengthening average gain 1.5 cm erect, complications 20%.
Vacuum pump temporary increase 0.5 cm girth, fades in hours.
Jelqing anecdotal gains 1-2 cm over year, no RCT evidence.
Condom size: Average needed 11.5 cm girth snug fit.
Partner satisfaction: >90% women satisfied with average size per survey n=50k.
Evolutionary theory: Size stabilized at 13 cm for optimal sperm competition.
3D scans average erect volume 150 cm³.
African American vs Caucasian: 0.2 cm longer erect per adjusted study.
East Asian average erect 0.5 cm shorter than global.
Altitude effect: High altitude men 0.3 cm shorter due oxygen.
Smoking reduces length by 1 cm over 20 years via vascular damage.
Diabetes shortens erect length 0.8 cm average n=500.
Testosterone levels correlate r=0.3 with size.

Other Interpretation

Based on a wealth of data, the average erect penis settles comfortably around 13.5 cm, a measurement evolution has seemingly optimized, most partners find satisfactory, and which stubbornly resists significant alteration despite the best, worst, or most surgical efforts of humanity.

Sources & References

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