calcSD

Percentile calculator

The calcSD Average (v2)

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.


I. Ditching the Veale study

I didn't know this before, but this study is broken. Quite broken. Firstly, a lot of people report that it measures almost 15 thousand men, but in actuality that's only for Stretched Flaccid Lengths, for normal flaccid lengths there were about 10 thousand people and for erect length and girth there were only 700 and 400 people, respectively. That's certainly not 15 thousand! Previously, I tried to remedy this by combining the Stretched Flaccid Length average with the Erect Length average (as both are extremely correlated), as well as merging the study with Habous et al, 2015. It worked well...until I realized yet another problem.

Veale et al, 2015 mixes bone-pressed and non bone-pressed studies. Basically, bone-pressed (BP) measurements are pressed against the pubic bone, pushing the fat pad away. Non bone-pressed (NBP) studies don't do this, instead they measure it against the skin. For example, person A has 6" of BP length and a 1" fat pad, while person B has 7" of BP length but 3" of fat pad. This means that the NBP measurement of person A is going to end up at 5" and of person B at 4". The only thing that made person B smaller than person A, when comparing using NBP, is their body shape because one has more fat than the other. There are reasons to prefer BP or NBP, but I think we can all agree that these two types of measurements should not be mixed together.

The problematic study used in Veale, which is also used in Hungfun's Average, is Wessells et al. 1996. It provides NBP measurements in an otherwise entirely BP study. In Veale et al.'s case, there's others as well such as Aslan et al. 2011. This, among other errors pointed in the Veale meta-study, are the reason that I have to demote it from its main position from the site. It's now going to be listed as a non-recommended study along with Hungfun's Average, and it will be removed from the calcSD Average as well.

But this poses a problem: without the Veale study, the calcSD Average only has one study in it, Habous et al, 2015. What can be done to solve this?


II. The Phosphine Average

There was one person who merged a few reliable studies and made an average of their own. They didn't want their name attributed to it, so I had to create one. The studies they used were Chen J et al. 2000, Promodu et al. 2007, Chen XB et al. 2014 and Habous et al. 2015. Abbreviated, it makes CPCH, or C2HP, which is the chemical formula for an element in the Phosphine group. That's why I named it the Phosphine Average. Yes, I know, puns.

All four of these studies are bone-pressed, while the circumference measurement is mixed between base-shaft and mid-shaft. The calculations were done by dividing the number of people in a specific study by the number of people total, and multiplying that value by the average and standard deviation (separately). Then, the sum of all averages and SDs will provide the combined average. For reference, Chen J had 55 participants, Habous had 778, Promodu had 41 and 301 (erect and flaccid, respectively) and Chen XB had 311 and 5196. For the Promodu study, Group 3 was used instead of Group 2, as the latter was self-reported. The numbers are as follows:


Study Avg. Erect Length (SD) Avg. Erect Girth (SD) Avg. Flaccid Length (SD) Avg. Flaccid Girth (SD) Avg. Stretched Flaccid (SD)
Chen J et al. 2000 13.60cm (1.70) 5.35" (0.67) 10.90cm (1.60) 4.29" (0.63) 8.30cm (1.30) 3.27" (0.51) 8.10cm (1.50) 3.19" (0.59) 12.50cm (1.40) 4.92" (0.55)
Promodu et al. 2007 12.93cm (1.63) 5.09" (0.64) 11.49cm (1.04) 4.52" (0.41) 8.21cm (1.44) 3.23" (0.57) 9.14cm (1.02) 3.60" (0.40) 10.88cm (1.42) 4.28" (0.56)
Chen XB et al. 2014 12.90cm (1.30) 5.08" (0.51) 10.50cm (0.90) 4.13" (0.35) 6.50cm (0.70) 2.56" (0.28) 8.00cm (0.80) 3.15" (0.31) 12.90cm (1.20) 5.08" (0.47)
Habous et al. 2015 14.34cm (1.86) 5.65" (0.73) 11.50cm (1.74) 4.53" (0.69) N/D N/D N/D N/D N/D N/D
Phosphine Average 13.88cm (1.70) 5.46" (0.67) 11.21cm (1.49) 4.41" (0.59) 6.61cm (0.75) 2.60" (0.30) 8.06cm (0.82) 3.17" (0.32) 12.79cm (1.21) 5.04" (0.48)

There's a few reasons why this didn't become the calcSD Average though:

  1. I wasn't the one who made it.
  2. I'd like to be able to include more studies on the main average.
  3. I didn't want to include the Chen 2014 study, because of its weirdly low numbers and the high impact it would make on the flaccid size statistics.

III. Gathering More Studies

Searching for new studies is more convoluted than it should be. Firstly, most articles are hidden behind a paywall, which is fine until they decide to leave out important information from the abstract, like the measuring method or the standard deviation. Secondly, trying to gather that data by other means is a tedious process of looking through many pages, images and tables and hoping that one of the people that made them was generous enough to put the necessary info there.

Thankfully, I believe I have been able to find enough data to form the new calcSD Average, but I still feel like there's more things I'm missing. If there's anything I've overlooked, or if there's more reliable studies to include or something wrong in any of the ones that I've included, please feel free to contact me about it.


IV. Processing the Current Average

Currently, the average includes 9 studies total:

The Wessells et al. 1996, LifeStyles Condoms and Promodu et al. 2007 use mid-shaft girth measurements, while Chen J. et al. 2000 uses base-shaft girth. Other studies' methods are unknown. Schneider et al. 2001 measured the width (diameter) and calculated it into a circumference by assuming a perfect cylinder and using the following formula: C = d × π


Study Avg. Erect Length (SD) Avg. Erect Girth (SD) Avg. Flaccid Length (SD) Avg. Flaccid Girth (SD) Avg. Stretched Flaccid (SD)
Habous et al. 2015 14.34cm (1.86) 5.65" (0.73) 11.50cm (1.74) 4.53" (0.69) N/D N/D N/D N/D N/D N/D
LifeStyles Condoms 14.93cm (2.10) 5.88" (0.83) 12.63cm (1.29) 4.97" (0.51) N/D N/D N/D N/D N/D N/D
Acuña et al. ???? 13.90cm (1.70) 5.47" (0.67) N/D N/D 8.95cm (1.50) 3.52" (0.59) N/D N/D 13.60cm (1.60) 4.92" (0.55)
Schneider et al. 2001 14.48cm (1.99) 5.70" (0.78) 12.41cm (1.19) 4.89" (0.47) 8.60cm (1.50) 3.39" (0.59) 9.68cm (1.26) 3.81" (0.50) N/D N/D
Promodu et al. 2007 12.93cm (1.63) 5.09" (0.64) 11.49cm (1.04) 4.52" (0.41) 8.21cm (1.44) 3.23" (0.57) 9.14cm (1.02) 3.60" (0.40) 10.88cm (1.42) 4.28" (0.56)
Chen J et al. 2000 13.60cm (1.70) 5.35" (0.67) 10.90cm (1.60) 4.29" (0.63) 8.30cm (1.30) 3.27" (0.51) 8.10cm (1.50) 3.19" (0.59) 12.50cm (1.40) 4.92" (0.55)
calcSD Average (BP) 14.32cm (1.88) 5.64" (0.74) 11.80cm (1.56) 4.65" (0.61) 8.45cm (1.45) 3.33" (0.57) 9.15cm (1.13) 3.60" (0.45) 11.79cm (1.47) 4.64" (0.58)
Number of people: 1467 1337 597 467 486

Study Avg. Erect Length (SD) Avg. Erect Girth (SD) Avg. Flaccid Length (SD) Avg. Flaccid Girth (SD) Avg. Stretched Flaccid (SD)
Habous et al. 2015 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
Aslan et al. 2011 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)
Park et al. 1998 11.88cm (1.32) 4.68" (0.52) 12.11cm (1.10) 4.77" (0.43) 7.76cm (1.19) 3.06" (0.47) 9.02cm (1.16) 3.55" (0.46) 12.30cm (1.33) 4.84" (0.52)
Wessells et al. 1996 12.89cm (2.91) 5.07" (1.15) 12.30cm (1.31) 4.84" (0.52) 8.85cm (2.38) 3.48" (0.94) 9.71cm (1.17) 3.82" (0.46) 12.45cm (2.71) 4.90" (1.07)
calcSD Average (NBP) 12.39cm (1.85) 4.88" (0.73) 11.71cm (1.55) 4.61" (0.61) 8.98cm (1.34) 3.54" (0.53) 9.17cm (1.16) 3.61" (0.46) 13.37cm (1.61) 5.26" (0.63)
Number of people: 1145 1145 1499 367 1499


Last update: Nov. 25, 2017 (calcSD v1.8)