Sunday, October 2, 2011

The simple truth about erect penis circumference

Average erect penis circumference Here is an example of irrelevant and misleading information:

Just under three thousand (2,936) men took part in a DUREX survey – most of them under 25 – from all over the world. They self-reported their erect length and circumference. Both length and circumference vary quite widely but, in each case, there is an average value and in this survey they were 163 mm (6.4 inches) for erect length and 133 mm (5.2 inches) for erect circumference.

This is typical of surveys released publicly with absolutely no scientific background nor interest. Why then? It is unclear why manufacturers would release such information.

Below you will find a collection of true scientific studies, ie. anybody can re-produce it following the exact same protocols.
* Are included in the scientific average only the studies where the medical staff did the measuring or ensured a proper training.
** The average erect circumference was extrapolated from the measured erect width considering the penis is a cylinder.

So basically, true scientific studies, where medical staff are conducting, training and often performing the measurement, come short of up to 1cm (0.4in) compared with non-scientific internet surveys.

NB: I didn't report data for length as it is not really relevant for choosing the right condom. As an example though, the Wessel Study came up with the following results: Erect length: 128.9mm (sd 29.1mm), fat pad : 28.5mm (sd 15.9mm), Functional erect length (Erect length non pubic bone pressed plus fat pad): 157.4mm (sd 26.2mm). This last result is consistent with the Kinsey data. To finish with erect penis length, the average (obtained by pressing the ruler on the pubic bone) from the scientific studies* above, is 147.64mm (sd 19.78mm).

So the real average erect circumference, or average erect penis girth, is around 121-123 mm.

See here for further details:

The average erect penis girth may be even smaller than previously thought

Wessells H, Lue TF, McAninch JW. Penile length in the flaccid and erect states: guidelines for penile augmentation. J Urol 1996; 156: 995-997.
Janssen. "Penile Circumference Variability - in a Dutch Sample (1994)". Faculty of Psychology University of Amsterdam.
Schneider T, Sperling H, Lummen G, Syllwasschy J, Rubben H. "Does penile size in younger men cause problems in condom use? A prospective measurement of penile dimensions in 111 young and 32 older men". Urology 2001; 57: 314-318.
da Ros C. "Caucasian penis: what is the normal size?". J Urol 1994; 151: 323A.
Richard Harding, M.Sc. and Susan E. Golombok, Ph.D."Test-Retest Reliability of the Measurement of Penile Dimensions in a Sample of Gay Men"

Other references:
Penile Size and Penile Enlargement Surgery: A Review: Penile Size


  1. There^s only 4 here measured by staff.Problem is the Da Ross has a 4.7 at the base of the penis(the proximal) & a 4.4 mid range(not reported) in this list . Wessel had 4.8 mid range. One German report had 4.33(base ?, Mid range ?). The results are inconclusive due to different methodolgy or unknown procedure. self measurements count for squat

  2. Well, you are right. Not enough detail is given ususally in studies or reports of studies and no widely shared and accepted standard exists when it comes to measuring the erect penis girth.

    The purpose of this blog is not to pretend having the definite answer on the subject (and it is not important after all). The main purpose is just to present objective erect penis circumference values (which indicate that it is consistently below what most people believe) in order to demonstrate that one can use it to "guess" its proper condom size. Few mm, or tenth of an inch will not drastically modify the results, nor question the consistency of the current data.

  3. Do you know if there is any information on whether or not the length on the lifestyles study was done bone pressed?

  4. The Lifestyle study should be ignored as it can not be considered as a scientific study (means, protocols, raw data...).

  5. True, but It if measured non bone pressed, it does come closer to what I believe the average to be which is roughly 6 non bone pressed. I find it hard to believe that the average is 5.8 bone pressed, thats somewhere around 5-5.4" non bone pressed, which seems way to small to me. Even if it is not to be considered when discussing average size, do you have any knowledge of it being bone pressed or non bone pressed?

  6. ^^ Meaning the lifestyles study ***

  7. Without any further explanation from the testers, it is pure speculation and supposition, therefore meaningless.

  8. Good point. I do find it particularly peculiar that the wessels study, while measuring 5.1" non bone pressed, measured a whopping 1.2" average fat pad on the men it measured. This puts the bone pressed average almost at 6.3" which is alot higher than many of the other clinician measured studies.

  9. I did email lifestyles to see if I could get an answer, but i'm not going to get my hopes up.

  10. The Wessells data shows a "mean" Erect Length of 5.07" + Fat Pad Depth of 1.12" for what they call a Functional Length (BPEL) of 6.20". That is misleading though, as participants were broken out into younger or older than 40 yrs old, to account for increasing fat pad depth as men age. Looking at the mean data by age group we come up with:
    < 40 yrs old = 5.24" Erect Length(NBPEL) + 0.70" Fat Pad = 5.94" Functional Length (BPEL)
    > 40 yrs old = 4.83" Erect Length(NBPEL) + 1.20" Fat Pad = 6.04" Functional Length (BPEL)

    Some quotes from the body of the paper:
    - "Measurements were made of the erect length from the pubo-penile skin junction to the meatus, circumference at mid-shaft, and the fat pad depth."
    - "Functional penis length was defined as the sum of the erect length plus the fat pad depth."

  11. Very interesting piece of information I was not aware of. But I am not really interested in penis length. I provided the length data for information purpose only.

    Rather, can you provide the details for the erect penile circumference, as well as the number of participants for each group?

  12. See here:

  13. As a point of information, both the means listed and the standard deviations aren't representative of the actual situation. Biological statistics are almost always skewed to the right. The lower limit is zero and the upper limit is infinity. Due to this, if an average is 5, there are more likely to be statistics greater than 10 than there are less than zero. In layman's terms, mean isn't very useful as a method of comparison.

    In right skewed statistics, the mean is greater than the median. The median represents the point at which 50% are below and 50% are above. THIS IS NOT THE SAME AS THE MEAN. How does that effect the cited numbers? Having an average penis size means that you are actually greater than the 50th percentile, or that more people are smaller than larger.

    The Jannsen study in the chart above lists the average as 122mm. However, in their actual study they list the median at 118mm, which is the real 50% point. To add even more to the below average worriers, the absolute range they provide is 90mm to 160mm. So the lower limit is 28mm below the median and the upper limit is 42mm above it. This means that the bottom 50% are actually grouped in a tighter range than the top 50%. Basically... don't stress if you're below. There is less of a deviation downwards than upwards, therefore less of a chance for it to be actually noticeable.

    Quick example to emphasize the point. 5 subjects measuring 118,118,118,118 and 138. The average is 122, the median is 118. 80% are below the mean which is hardly representative of the population.

    1. And to quickly add on to that, given that the median circumference is 118mm, the condom needed to stretch to 15% is 102mm in circumference. Oddly (fully sarcastic), this is a 51mm condom.

    2. Sorry, one last point of information. I forgot to mention why standard deviation is a poor measurement. Standard deviation puts 68% of subjects within +- 1sd of the mean. But since mean =/= median, I've stated that this simply isn't accurate. The best way to give helpful information is to use simple percentiles. Again based on the Jannsen study:

      0-25% are within 90-109mm, range of 19mm
      25-50% are within 109-118mm, range of 9mm
      50-75% are within 118-132, range of 14mm
      75-100% are within 132-160, range of 28mm

      This shows a tighter distribution around the Using these numbers and the reported mean and sd of this study, the 25th percentile if normally distributed would be 111.25. Basically this means anyone from 109<= x <111.25 would think they are in the bottom 25% when this is simply untrue.

    3. You are totally right about the difference between mean and median.

      But on quality scientific studies, it looks like the differences vanish a little bit (they are not so important).

      The Jannsen stud is a good example (only 4mm fifference between mean and median):
      Percentile P25 P50 P75 P90
      measured on study 110 118 131 142 (data used from Response > 10 mm
      calculated 112 122 133 143
      (assuming a normal repartition)

      Few millimeters are to be neglected and do not change radically the conclusions.

      On the contrary a bad study such as the Lifestyles one has a huge gap between median (4.67in) and the mean (4.97in) and the study is full of bias, the most important one being the selection of participating individuals.

  14. This comment has been removed by a blog administrator.

  15. I think the one factor that people often forget is that even if only 0.1% of the population has penis girth sizes larger than 160 mm, that is still 135 thousand males in the US who can't buy proper fitting condoms since it is currently illegal to sell condoms over the 58mm mark. Being large is just a pain both literally and figuratively. If given the choice I would be happy to have a smaller "normal" sized erect penis.

  16. This comment has been removed by a blog administrator.