calcSD

Penis Percentile Calculator

The calcSD Average (v4)

Sometimes we change so many things that we need a page just talking about all the changes. This page details the calcSD Average, how it was achieved and what composes it. If you're looking for the previous version of the calcSD Average, it's still available here.


This page highlights the studies that were used to create the calcSD Global Average v4, how they were chosen and how an average is calculated from all the data they provide.


Gathering Even More Studies

Searching for new studies is more convoluted than it should be. Firstly, most articles are hidden behind a paywall, fortunately there are online tools for circumventing those. Secondly, trying to gather that data is a tedious process of looking through many pages, images and tables hoping that the people that made them were generous enough to publish the necessary info.

Through great effort we've compiled the data of a vast number of these studies to form the new calcSD Average. Quite a few minor corrections were made for this update, further corrections will be kept within this v4, allowing simple comparison to the previous v3 average to see corrections (a v5 will only be made if enough compulsory randomly-sampled researcher-measured studies are published in the future to be able to draw definitive conclusions without the issue of selection/volunteer bias). If there's anything we've overlooked, or if there are more reliable studies to include or something wrong in any of the ones that we've included, please feel free to contact us about it.


This average utilizes a weighting that is 50% weighted by sample size and 50% weighted equally to each study. The rationale for this is that studies with larger sample sizes have a lower margin of error and should therefore be weighted more than lower sample size studies, however they do not have any improvement to potential biases. If solely weighted by sample size, a study with thousands of men sampled would effectively make negligible other studies of only hundreds of individuals. This would bias the resulting average in favor of a few larger studies with biases that may not accurately reflect the general population. So to reduce the risk of skewing the results towards the biases of a small portion of studies with very large sample sizes, the weighting is cut halfway towards uniform weighting of each study. This 50:50 weighting is done for both mean and SD. But for SD, the mathematically correct way to get an average SD is to average the variances (SD²) and then take the square root to get the average SD. This is called the pooled SD, which utilizes an almost negligible statistical modification to what is otherwise just a sample size weighted average. As previously mentioned, the pooled SD is then cut halfway towards a uniform weighting.

Additionally, to make this average more representative of the general adult population, we have excluded:


Currently, the average includes a total of 56 studies:

Study Avg. BP Erect Length (SD) Avg. NBP Erect Length (SD) Avg. Erect Girth (SD) Avg. Flaccid Girth (SD) Avg. BP Flaccid Length (SD) Avg. NBP Flaccid Length (SD) Avg. BP Stretched Length (SD) Avg. NBP Stretched Length (SD)
Acuña et al. 1999 13.90cm (1.70) 5.47" (0.67) N/D N/D N/D N/D N/D N/D 10.49cm (1.30) 4.13" (0.51) 8.95cm (1.50) 3.52" (0.59) 13.60cm (1.60) 5.35" (0.63) N/D N/D
Ajmani et al. 1985 21-23yrs N/D N/D N/D N/D N/D N/D 8.87cm (0.97) 3.49" (0.38) N/D N/D 8.26cm (1.52) 3.25" (0.60) N/D N/D N/D N/D
Ali & Ali 2012 N/D N/D 13.70cm (1.6) 5.39" (0.63) 12.60cm (1.50) 4.96" (0.59) 8.30cm (1.20) 3.27" (0.47) N/D N/D 9.30cm (1.30) 3.66" (0.51) N/D N/D N/D N/D
Aslan et al. 2011 N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D 9.30cm (1.30) 3.66" (0.51) N/D N/D 13.70cm (1.60) 5.39" (0.63)
Awwad et al. 2005 Group 1 N/D N/D N/D N/D N/D N/D 8.98cm (1.50) 3.54" (0.59) 9.30cm (1.90) 3.66" (0.75) N/D N/D 13.50cm (2.30) 5.31" (0.91) N/D N/D
Barboza et al. 2018 N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D 16.06cm (1.64) 6.32" (0.64) N/D N/D
Bondil et al. 1992 N/D N/D N/D N/D N/D N/D N/D N/D 10.74cm (1.84) 4.23" (0.72) N/D N/D 16.74cm (2.29) 6.59" (0.90) N/D N/D
Chaurasia & Singh 1974 N/D N/D N/D N/D N/D N/D 8.77cm (0.70) 3.45" (0.28) N/D N/D 7.36cm (0.77) 2.90" (0.30) N/D N/D N/D N/D
Chen et al. 2000 13.60cm (1.70) 5.35" (0.67) N/D N/D 10.90cm (1.60) 4.29" (0.63) 8.10cm (1.50) 3.19" (0.59) 8.30cm (1.30) 3.27" (0.51) N/D N/D 12.50cm (1.40) 4.92" (0.55) N/D N/D
Chen et al. 2014 12.90cm (1.30) 5.08" (0.51) N/D N/D 10.50cm (0.90) 4.13" (0.35) 8.00cm (0.80) 3.15" (0.31) N/D N/D 6.50cm (0.70) 2.56" (0.28) 12.90cm (1.20) 5.08" (0.47) N/D N/D
Choi et al. 2011 N/D N/D N/D N/D N/D N/D N/D N/D 7.70cm (1.70) 3.03" (0.67) N/D N/D 11.70cm (1.90) 4.61" (0.75) N/D N/D
Eisenberg et al. 2011 Control N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D 11.95cm (2.27) 4.70" (0.89)
Eisenberg et al. 2012 OA N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D 12.54cm (2.03) 4.94" (0.80)
Farkas 1971 N/D N/D N/D N/D N/D N/D 9.57cm (0.83) 3.77" (0.33) N/D N/D 7.22cm (1.12) 2.84" (0.44) N/D N/D N/D N/D
Foresta et al. 2018 N/D N/D N/D N/D N/D N/D 9.40cm (1.10) 3.70" (0.43) 8.90cm (1.70) 3.50" (0.67) N/D N/D N/D N/D N/D N/D
Gabrich et al. 2007 18yrs N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D 14.50cm (1.60) 5.71" (0.63) N/D N/D
Habous et al. 2015[1] 14.34cm (1.86) 5.65" (0.73) 12.53cm (1.93) 4.93" (0.76) 11.50cm (1.74) 4.53" (0.69) N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D
Habous et al. 2015[2] 14.30cm (2.00) 5.63" (0.79) N/D N/D 11.60cm (1.50) 4.57" (0.59) 9.40cm (1.50) 3.70" (0.59) N/D N/D N/D N/D 11.7cm (1.60) 4.61" (0.63) N/D N/D
Haliloglu et al. 2007 N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D 14.20cm (1.10) 5.59" (0.43)
Hosseini et al. 2007 Control N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D 13.01cm (1.04) 5.12" (0.41)
Hussein et al. 2017 N/D N/D N/D N/D N/D N/D N/D N/D 9.80cm (2.00) 3.86" (0.79) N/D N/D 12.6cm (1.90) 4.96" (0.75) N/D N/D
Hwnag et al. 2005 Group 2 N/D N/D N/D N/D N/D N/D N/D N/D 8.07cm (1.19) 3.18" (0.47) N/D N/D 11.71cm (1.81) 4.61" (0.71) N/D N/D
Kamel et al. 2009 Group I N/D N/D N/D N/D N/D N/D N/A N/A N/D N/D N/D N/D 12.90cm (1.90) 5.08" (0.75) N/D N/D
Khan et al. 2012 N/D N/D N/D N/D N/D N/D N/D N/D 10.20cm (1.40) 4.02" (0.55) 8.70cm (1.56) 3.43" (0.61) 14.30cm (1.68) 5.63" (0.66) N/D N/D
LifeStyles Condoms (2001) N/A N/A N/A N/A 12.63cm (1.29) 4.97" (0.51) N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D
Mehraban et al. 2006 N/D N/D N/D N/D N/D N/D 8.66cm (1.01) 3.41" (0.40) N/D N/D N/D N/D N/D N/D 11.58cm (1.42) 4.56" (0.56)
Motofumi et al. 2012 N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D 9.41cm (1.54) 3.70" (0.61) N/D N/D 12.22cm (1.72) 4.81" (0.68)
Nasar et al. 2011 N/D N/D N/D N/D N/D N/D 10.48cm (0.69) 4.13" (0.27) N/D N/D 8.37cm (1.31) 3.30" (0.52) N/A N/A N/D N/D
Nguyen et al. 2021 Group 1 N/D N/D N/D N/D N/D N/D N/A N/A 8.99cm (1.01) 3.54" (0.40) N/D N/D 14.6cm (1.39) 5.75" (0.55) N/D N/D
Park et al. 1998 14.06cm (1.49) 5.54" (0.59) 11.88cm (1.32) 4.68" (0.52) 12.11cm (1.10) 4.77" (0.43) 9.02cm (1.16) 3.55" (0.46) N/D N/D 7.76cm (1.19) 3.06" (0.47) N/D N/D 12.3cm (1.33) 4.84" (0.52)
Park et al. 2011 N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D 10.76cm (1.92) 4.24" (0.76)
Park et al. 2016 13.53cm (1.68) 5.33" (0.66) N/D N/D N/D N/D N/D N/D 7.39cm (1.52) 2.91" (0.60) N/D N/D N/D N/D N/D N/D
Pereira 2004 N/A N/A N/D N/D N/D N/D 9.39cm (1.05) 3.70" (0.41) 9.86cm (1.84) 3.88" (0.72) N/D N/D 15.14cm (2.12) 5.96" (0.83) N/D N/D
Ponchietti et al. 2001 N/D N/D N/D N/D N/D N/D 10.00cm (0.75) 3.94" (0.30) N/D N/D 9.00cm (2.00) 3.54" (0.79) N/D N/D 12.50cm (2.50) 4.92" (0.98)
Promodu et al. 2007 Groups 1 & 3 N/D N/D 12.93cm (1.63) 5.09" (0.64) 11.49cm (1.04) 4.52" (0.41) 9.14cm (1.02) 3.60" (0.40) N/D N/D 8.21cm (1.44) 3.23" (0.57) N/D N/D 10.88cm (1.42) 4.28" (0.56)
Rad 2020 N/D N/D N/D N/D N/D N/D 8.50cm (0.76) 3.35" (0.30) N/D N/D 7.87cm (1.46) 3.10" (0.57) N/D N/D 12.22cm (2.44) 4.81" (0.96)
Salama 2015[1] Control 15.00cm (1.80) 5.91" (0.71) 13.00cm (1.70) 5.12" (0.67) 11.80cm (1.00) 4.65" (0.39) 8.98cm (0.90) 3.54" (0.35) 10.02cm (1.90) 3.94" (0.75) 8.05cm (1.80) 3.17" (0.71) N/D N/D N/D N/D
Salama 2015[2] Control 15.04cm (1.51) 5.92" (0.59) 12.88cm (1.46) 5.07" (0.57) 11.92cm (1.06) 4.69" (0.42) 9.14cm (0.89) 3.60" (0.35) 10.00cm (1.56) 3.94" (0.61) 7.81cm (1.31) 3.07" (0.52) N/D N/D N/D N/D
Savoie et al. 2003 N/D N/D N/D N/D N/D N/D 9.40cm (1.40) 3.70" (0.55) N/D N/D 9.30cm (2.00) 3.66" (0.79) N/D N/D 13.50cm (2.60) 5.31" (1.02)
Schneider et al. 2001 Group A 14.48cm (1.99) 5.70" (0.78) N/D N/D N/A N/A N/A N/A 8.60cm (1.50) 3.39" (0.59) N/D N/D N/D N/D N/D N/D
Shalaby et al. 2014 N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D 13.84cm (1.35) 5.45" (0.53) N/D N/D
Siminoski et al. 1993 N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D 9.40cm (1.4) 3.70" (0.55)
Son 1999 11.90cm (1.30) 4.69" (0.51) 10.80cm (1.30) 4.25" (0.51) 11.30cm (1.2) 4.45" (0.47) 8.90cm (0.80) 3.50" (0.31) N/D N/D 6.10cm (1.30) 2.40" (0.51) N/D N/D 9.60cm (1.20) 3.78" (0.47)
Son et al. 2003 N/D N/D N/D N/D N/D N/D 8.50cm (1.10) 3.35" (0.43) N/D N/D 6.90cm (0.80) 2.72" (0.31) N/D N/D 9.80cm (0.80) 3.86" (0.31)
Soylemez et al. 2011 N/D N/D N/D N/D N/D N/D 8.89cm (0.86) 3.50" (0.34) 8.95cm (1.04) 3.52" (0.41) N/D N/D 13.98cm (1.58) 5.50" (0.62) N/D N/D
Spyropoulos et al. 2002 N/D N/D N/D N/D N/D N/D 8.68cm (1.12) 3.42" (0.44) N/D N/D N/D N/D N/D N/D 12.18cm (1.70) 4.80" (0.67)
Stewart et al. 2009 N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D 15.00cm (1.70) 5.91" (0.67) N/D N/D
Tomova et al. 2010 19yrs N/D N/D N/D N/D N/D N/D 9.67cm (0.91) 3.81" (0.36) N/D N/D 9.46cm (1.12) 3.72" (0.44) N/D N/D N/D N/D
Vasconcelos et al. 2012 No ED N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D 16.60cm (1.70) 6.54" (0.67) N/D N/D
Wang & Li 1989 N/D N/D 13.00cm (1.30) 5.12" (0.51) N/A N/A N/A N/A N/D N/D 7.10cm (1.50) 2.80" (0.59) N/D N/D N/D N/D
Wessells et al. 1996 15.74cm (2.62) 6.20" (1.03) 12.89cm (2.91) 5.07" (1.15) 12.30cm (1.31) 4.84" (0.52) 9.71cm (1.17) 3.82" (0.46) N/D N/D 8.85cm (2.38) 3.48" (0.94) N/D N/D 12.45cm (2.71) 4.90" (1.07)
Wu et al. 1990 N/A N/A N/D N/D N/D N/D N/D N/D 7.92cm (1.04) 3.12" (0.41) 6.62cm (1.02) 2.60" (0.40) 13.90cm (1.13) 5.47" (0.44) N/D N/D
Wu et al. 1994 N/D N/D N/D N/D N/D N/D 8.19cm (0.61) 3.22" (0.24) 7.36cm (0.95) 2.90" (0.38) N/D N/D 13.33cm (1.12) 5.25" (0.44) N/D N/D
Wu & Yang 1993 13.51cm (1.08) 5.32" (0.43) N/D N/D 11.03cm (0.83) 4.34" (0.33) 8.48cm (0.76) 3.34" (0.30) 8.04cm (1.10) 3.17" (0.43) 6.91cm (1.16) 2.72" (0.46) 13.81cm (1.15) 5.46" (0.45) N/D N/D
Yoon et al. 1998 N/D N/D 13.42cm (1.38) 5.28" (0.54) 11.17cm (1.05) 4.40" (0.41) 8.34cm (1.03) 3.28" (0.41) N/D N/D 8.26cm (1.07) 3.25" (0.42) N/D N/D N/D N/D
Zhu et al. 1990 N/D N/D N/A N/A N/A N/A N/A N/A N/D N/D 6.90cm (1.40) 2.72" (0.55) N/D N/D N/D N/D
calcSD Global Average 13.98cm (1.72) 5.50" (0.68) 12.64cm (1.71) 4.98" (0.67) 11.64cm (1.31) 4.58" (0.52) 8.94cm (0.96) 3.53" (0.37) 8.96cm (1.41) 3.53" (0.55) 7.92cm (1.39) 3.11" (0.55) 13.82cm (1.59) 5.44" (0.63) 12.11cm (1.93) 4.77" (0.76)
Number of people: 2647 2078 2834 19433 11960 15865 19777 8271
Highest Maximum: 21cm 8.27" 19cm 7.48" 16cm 6.30" 14cm 5.51" 20cm 7.87" 16cm 6.30" 27cm 10.63" 21cm 8.27"
Lowest Minimum: 7cm 2.76" 4cm 1.57" 5cm 1.97" 2cm 0.79" 3cm 1.18" 3.5cm 1.38" 5cm 1.97" 6cm 2.36"
BP Erect Length NBP Erect Length Erect Girth Flaccid Girth BP Flaccid Length NBP Flaccid Length BP Stretched Length NBP Stretched Length

Last updated: Aug. 23, 2021