Geographic variation in human penis size

Can we look at this as simply another study in geographic variation of the human species?  Probably not, for males who see this map will undoubtedly find their hands reaching for a ruler.

It’s a world map of penis sizes (erect). Note that the tumescent lengths are in centimeters; divide by 2.54 to get inches. If you go to the link and click on the map there, you’ll also see an extensive list of country-by country-values measured in both inches and centimeters, as well as some sources of the data, which were apparently collected and collated from various other sources by Dr. Eduardo Gomez de Diego.  Gomez de Diego has made something of a career out of measuring schlongs.

I’m not going to put my reputation behind these data, but present them for your salacious delectation.

Dare I say “click to enlarge”?

Some thoughts, assuming that the data are accurate:

  • If you want to pursue this further, Wikipedia (naturally) has a big article on penis size, full of intriguing tidbits like this: “Results vary, with studies that rely on self-measurement reporting a significantly higher average than those with staff measuring, but a mean erect human penis is approximately 12.9–15.0 cm (5.1–5.9 in) in length. Flaccid penis length is a poor estimate of erect length.”  And this: “several scientific studies have been performed on the erect length of the adult penis. Studies which have relied on self-measurement, including those from Internet surveys, consistently reported a higher average length than those which used medical or scientific methods to obtain measurements”
  • The data from the chart show that the least endowed males are those from Thailand (10.16 cm or 4 inches) and India (10.24 cm, also 4 inches), while the length champions hail from the Congo at 17.93 cm (7.1 inches).
  • These data are not normalized for body size.  If there is a correlation within populations between body size (measured as length of other parts, like legs) and erect penis size—and Wikipedia is ambiguous on this—then perhaps penis-length values should be relative (i.e. erect penis length/leg length) rather than absolute ones.  It’s possible, for example, that some of the large schlong values from the Congo are due to its inhabitants simply being bigger than Indians.
  • If these data reflect genetic differences (and that could be verified by measuring the offspring of people who have moved to other locations), and don’t normalize to equal sizes (which I suspect they won’t), then one can speculate about their evolutionary origins.   I could make up stories about mate competition or sexual selection, but I’ll spare you.  Evolutionary psychologists are much better at this than I.  Larry Moran, however, might say that the population differences simply reflect genetic drift.
  • The biggest penises are found in populations between the Tropic of Cancer and Tropic of Capricorn.  According to Allen’s Rule, which specifies that protruding body parts tend to be larger in populations inhabiting warmer climes (they serve as useful heat radiators, like the huge ears of desert rabbits), perhaps penises helped cool our ancestors.  Note: I’m kidding—although there is an Allen’s Rule for animal body parts like ears, limbs, and tails.

It has not escaped my notice that Dr. Gomez de Diego is also CEO of a company called Andromedical, which, according to his blurb, has developed a device to stretch the penis:

Dr. Gomez de Diego, developer of the Andro-Penis®, the top sold penile extender in the world, explained, “with a penile extender the size of the penis can increase 1.2 to 2.0 inches (3-5 cm), with a 97.5 percent rate of efficiency. All this is achieved without an expensive operation, without pain and it is permanent.”

I don’t think so!  And others are equally dubious.

You can see pictures of the Andro Penis Extender here and here (I used to have them up, but the vindictive doctor has threatened me for reproducing his photos without permission, although WordPress says that it’s fair usage.) Nevertheless, go see the stupid quack’s devices that promise to stretch your willy.


  1. Posted March 21, 2011 at 9:23 am | Permalink

    It’s on a website “Disinformation”, why would you think it is true? 🙂

  2. Posted March 21, 2011 at 9:27 am | Permalink

    self-measurement reporting a significantly higher average than those with staff measuring

    heh, “staff measuring”.

    • Phil65
      Posted March 21, 2011 at 2:07 pm | Permalink

      Well, this one is a no-brainer. When are you likely to have bigger wood, when you’re by yourself having one off the wrist, or when you’re standing in a lab while some stranger holds a ruler next to your John Thomas?

  3. Posted March 21, 2011 at 9:29 am | Permalink

    The chart shows Canadians having bigger penises than Americans. This must be incorrect! I mean, dude, we fight way more wars than Canada. How could our dicks be smaller?!?

    • Posted March 21, 2011 at 9:38 am | Permalink

      We need our guns to compensate, I guess.

    • Posted March 21, 2011 at 5:22 pm | Permalink

      It’s a good job you’ve got Samuel L Jackson, pulling you out of the ‘red zone’…

    • Dave
      Posted March 21, 2011 at 5:38 pm | Permalink

      We Canadians have less to prove!

      • Veronica Abbass
        Posted March 21, 2011 at 5:49 pm | Permalink

        “We Canadians have less to prove!” is an ambiguous statement.

        Is it a compliment or an insult?

    • Andrew
      Posted March 21, 2011 at 7:05 pm | Permalink

      This makes no sense to me. The USA and Canada have been settled by people from similar countries in similar ratios, haven’t they? The main exception is that the USA has more blacks, which would tend to give the USA a greater average length.

      • Posted March 21, 2011 at 7:58 pm | Permalink

        I think the US also has a much larger Asian population, which would drive the average the other way…

        And I’m not saying one more word on this thread, but will read with interest…;-))

        • Diane G.
          Posted March 22, 2011 at 12:46 am | Permalink

          LOL. You may have already said more than enough… 😀

        • Sigmund
          Posted March 22, 2011 at 2:48 am | Permalink

          I think the asian percentage of the US population is less than the percentage of asian population of Canada. In the US I think its only in the range of a few percent so it’s unlikely to affect the overall average.
          Given that my wife is Japanese you might think that I could have an amusing anecdote to add to the frivolous aspect to this thread but, frankly, I’m not in the mood. You see, looking at the Irish data I realize to my consternation that I must be adopted! Time to search for my real Mom and Dad! Anyone know the number of the Kinshasa adoption agency?

          • Posted March 22, 2011 at 6:26 am | Permalink

            …and my husband is Japanese 😉 Over which I shall draw a veil…

  4. MadScientist
    Posted March 21, 2011 at 9:33 am | Permalink

    I guess the author of the chart willfully ignores all the data which indicate that willies can’t be augmented with the gizmos available on the market. Even people with massive earrings take a while before the tissue shows obvious signs of permanent deformation – and that’s primarily deformation of skin. In the case of the penis, the corpus cavernosum will somehow need to be stretched.

  5. JS1685
    Posted March 21, 2011 at 9:34 am | Permalink

    It’s the internet. Clicking to enlarge will happen with or without your say-so.

  6. HP
    Posted March 21, 2011 at 9:36 am | Permalink

    If I had a large penis, I’d certainly feel cooler.

    • NewEnglandBob
      Posted March 21, 2011 at 10:32 am | Permalink

      You win 74 Internet points for that one! I was laughing so hard, I started to drool.

      • Posted March 21, 2011 at 10:53 am | Permalink

        “Not that there’s anything wrong with that.”
        — Jerry Seinfeld

      • HP
        Posted March 21, 2011 at 1:35 pm | Permalink

        It’s not every day I hear the word “drool” in the context of my penis.

  7. Posted March 21, 2011 at 9:41 am | Permalink

    Everyone knows that width > length. Right?


    • Scote
      Posted March 21, 2011 at 11:10 am | Permalink

      Tuna can disproves the universality of your thesis.

      However, I’ll concede that the data should include cubic displacement/volume to be of more complete relevance.

  8. Grania Spingies
    Posted March 21, 2011 at 9:43 am | Permalink

    I’m guessing that conception happens by wind pollination in countries like Saudi Arabia.

    • Dominic
      Posted March 21, 2011 at 10:02 am | Permalink

      Very good!

  9. Lars Karlsson
    Posted March 21, 2011 at 9:43 am | Permalink

    A study relying partly on self reporting done by a company with a bogus product to sell.

    So just because it’s on a nice interactive map it’s worth our time now?

    Shame on you Jerry.

    ps. Don’t divide by 2.54, grow up. =)

    • whyevolutionistrue
      Posted March 21, 2011 at 9:46 am | Permalink

      A. It’s not “self reporting”, which is defined as someone reporting their own penis size

      B. If you looked at the data below the map, you’d see that they come from a variety of different sources

      C. If you don’t like this website, go read someone else’s.

      • Lars Karlsson
        Posted March 21, 2011 at 10:34 am | Permalink

        I didn’t know self reporting had such a strict definition or that the result was to be seen as legit.

        I do like this site. Sorry for making you think I didn’t.

  10. Dominic
    Posted March 21, 2011 at 9:58 am | Permalink

    Clearly no relationship with the military size of a nation. Maybe inverse?! Seriously though, how can one compare countries of such huge geographical size as the USA, India, Russia & China, with small countries like Austria or Hungary?

    • Veronica Abbass
      Posted March 21, 2011 at 1:49 pm | Permalink


      You left out Canada: the world’s second largest country by total area.

      Re: the military size of a nation

      Military size isn’t everthing.

      • Dominic
        Posted March 21, 2011 at 3:23 pm | Permalink

        True! But again, the population is concentrated in certain areas is it not, particularly east & west? Russia is more populated & over a larger area. I am not boasting – the UK spends more on the military than most – more than France & look where they are – in the green zone (on the map)!

  11. Kevin
    Posted March 21, 2011 at 10:00 am | Permalink

    Just reminds me of the old joke:

    What’s 12 inches and white?


  12. Kevin
    Posted March 21, 2011 at 10:17 am | Permalink

    250 pounds!?

    It doesn’t look nearly that heavy. 🙂

    • Helen Wise
      Posted March 21, 2011 at 10:31 am | Permalink

      I was thinking the same thing, although from the laughing from the rest of the post and comments, I’ve almost shut the oxygen off to my brain.

      And also I think I fell in love with Dr.Coyne for his use of “salacious delectation”.

  13. Posted March 21, 2011 at 10:41 am | Permalink

    I’m at a public library right now, using socialist Wi-Fi. The picture won’t load.

    I’ll just shrug back and assume whatever I want. Comfortable delusions about my endowment.

  14. Sven DiMilo
    Posted March 21, 2011 at 11:07 am | Permalink

    with a 97.5 percent rate of efficiency

    What could this possibly mean? I’m familiar with energetic efficiency (output/input)…

    I give up.

    • Sven DiMilo
      Posted March 21, 2011 at 11:12 am | Permalink

      aha. I click da link.
      It should be “effectiveness,” not efficiency:

      Yes, finally we present the most effective device for a larger penis and the only way that was designed, developed and clinically tested by medical experts. At least 97.5% of users can be expected to significantly increase penis using the best breaking device in just a few months … and without no pills or operations that are dangerous and very expensive.

      and I can’t resist:

      Larger penis is your ticket for such a confident look that is unfeigned, or fiction, but true. Or suffer a lack of confidence and fears? Do you fear that you will be looking at women’s whiskey? Larger penis is a solution to your problem. The moment you will no longer fear, as women turn to become timid.

      Timidity, depression and low self-esteem have no chance against the very large penis and a rock solid erection that lasts much longer than before. Women are fascinated with your strong penis, which will always be in action and another man will observe with jealousy bulge in your pants. This is something I say, 100% rotation of the situation!

      • BilBy
        Posted March 21, 2011 at 12:44 pm | Permalink

        Women’s whiskey?! Do what now?!

  15. Posted March 21, 2011 at 11:08 am | Permalink

    > a career out of measuring schlongs

    Shouldn’t that be schlangs, since the Yiddish word is from the German Schlange, meaning snake?

    • Dominic
      Posted March 21, 2011 at 11:38 am | Permalink

      I am guessing it is the east European influence?

      Is Yiddish dying out?

      • Posted March 21, 2011 at 12:02 pm | Permalink

        I think schlong is a more phonetic spelling for an English-speaker, but the vowel sound for the “a” in Schlange is about the same in German .

        • Andrew
          Posted March 21, 2011 at 6:40 pm | Permalink

          It’s phonetic only if you’re speaking English with an American accent.

          • Posted March 21, 2011 at 9:22 pm | Permalink

            In American English, ‘schlong’ rhymes with ‘gong’ (not ‘long’). What does it sound like in British or other varieties of English?

            • Andrew
              Posted March 21, 2011 at 10:25 pm | Permalink

              Do ‘gong’ and ‘long’ really not have the same vowel sound in American English? I can’t think of any (other) variety of English in which they aren’t identical.

              • Sven DiMilo
                Posted March 22, 2011 at 4:05 am | Permalink

                It’s a pretty subtle difference, possibly regional. And I think it’s arguable which is closer to the intraregional pronunciation of schlong.

                In the extreme case, I believe that one of my students from Long Island would say something like ‘luong’–almost 2 syllables–and ‘gong’ pretty much the same, but would pronounce ‘schlong‘ like her grandfather who still has some legitimate Yiddish.

                I’ll try the experiment this week.

              • Sven DiMilo
                Posted March 22, 2011 at 4:06 am | Permalink

                come on, jerry, preview or edit, please.

              • Diane G.
                Posted March 22, 2011 at 11:42 am | Permalink

                Oh, to be a fly on the wall.

                “Yes, Professor?”
                “Say schlong.”

  16. SeanK
    Posted March 21, 2011 at 11:23 am | Permalink

    This map makes it very easy to find Hungary; the only dark-green spot in Europe.

    • Marella
      Posted March 21, 2011 at 4:21 pm | Permalink

      Which is odd since the Hungarians are supposed to have ridden in from the East where penises are much smaller.

      • Angel
        Posted March 22, 2011 at 5:27 am | Permalink

        Hungarian people, juste like those from Estonia and Finland (unlike every other indo-european people that make the rest of European populations) descend from the Finno-Ugrian tribes, who probably originate in western Ural mountains. Their languages are related to those of people from the extreme northern side of Russia, such as Samoyed, and Sami people of finnish Lapland, that do not share common ancesters with eastern asian people.

        So you should have to measure one of these norther tribe people, provided their ‘schlongs’ would be able to be fully erect under arctic siberian climates, to investigate for a possible origin of modern Hungarian’s well-endowement 😉

  17. Scote
    Posted March 21, 2011 at 11:26 am | Permalink

    It seems odd that males consider penis size such a vital aspect of sexual attractiveness yet the extreme variations in size in the population seem to suggest that it really isn’t a trait that is selected for.

    • Troy
      Posted March 21, 2011 at 12:07 pm | Permalink

      Not so fast. Large variation doesn’t necessarily indicate selective neutrality. Penis size could be a condition-dependent trait under sexual selection.

      It certainly would explain why female students from Germany are coming in droves to Dutch universities lately. Ahem.

      • Dominic
        Posted March 21, 2011 at 3:26 pm | Permalink

        Watch your bikes…

        • Troy
          Posted March 21, 2011 at 3:51 pm | Permalink

          Ooooh, that’s a subtle one.

          Let’s hope they bring their grandfather’s bike…

        • abadidea
          Posted March 21, 2011 at 9:07 pm | Permalink

          Not cool man.

  18. Posted March 21, 2011 at 11:40 am | Permalink

    I absolutely would NOT put my gizmo in that contraption; really, it looks like a torture device. Which it probably is.
    I don’t care how mean your erect penis is, that thing is going to hurt.

  19. Anonymous
    Posted March 21, 2011 at 12:13 pm | Permalink


    As it happens, another science blog I frequent recently featured this post:

    I haven’t read the original paper, so I can’t vouch for it’s quality.

    But it’s not very scientific of you to dismiss an empirical claim without evidence.

    Name Withheld

    • Sven DiMilo
      Posted March 21, 2011 at 12:42 pm | Permalink

      The data refer to increases in flaccid and stretched lengths, but do not mention erect lengths.

      My guess is that erection is still the great equalizer and that the observed increases are not functional.

      • Marella
        Posted March 21, 2011 at 4:10 pm | Permalink

        And who cares what flaccid length is?

        • Posted March 21, 2011 at 8:04 pm | Permalink

          Marella has a good point there…

        • Sven DiMilo
          Posted March 22, 2011 at 3:49 am | Permalink

          One has one’s reputation in the locker room or frathouse showers to think of, of course.

  20. Nancy
    Posted March 21, 2011 at 12:43 pm | Permalink

    Please do make up stories about mate competition or sexual selection – why should evolutionary psycholgists have all the fun?

    When is somebody going to do a study about penile girth?

    • Diane G.
      Posted March 21, 2011 at 3:49 pm | Permalink

      As soon as someone comes up with a suitable silicone implant to market…

      • Marella
        Posted March 21, 2011 at 4:11 pm | Permalink

        What about hyaluronic acid injections? Works for my lips!

        • Posted March 21, 2011 at 8:23 pm | Permalink

          The Ladies’ Section totally wins the thread! And why do they only ever talk about men’s size? You guys–

          …Horse-man and Deer-woman may be the highest union according to the Kama Sutra, but in practice it’s just uncomfortable. So fear not, you Men of the Hare–there is a Woman of the Deer out there for you;-)

          (Ladies’ Section, so I thought I’d just put in one more word…)

          • Diane G.
            Posted March 22, 2011 at 12:49 am | Permalink

            Say it, sister!

  21. Bing
    Posted March 21, 2011 at 12:43 pm | Permalink

    The map ( and presumably the research from which it derives ) supports at least one part of J. Phillipe Rushton’s work, that the Willy gets smaller in Eurasia, bigger in Africa and is in the middle wherever caucasians of northern European descent are found.

  22. Sam
    Posted March 21, 2011 at 1:16 pm | Permalink

    New Zealanders win the trans-Tasman rivalry forever! You tried well Aussies, but in the end you just didn’t measure up 😛

    • Marella
      Posted March 21, 2011 at 4:12 pm | Permalink

      I can’t help thinking that could be because of all those Maori, when in NZ go for the chocolate flavour, 😉

  23. occamseraser
    Posted March 21, 2011 at 1:53 pm | Permalink

    There is indeed a significant and positive correlation between body size (e.g., stature, even foot size) and penile length, but much of the variance cannot be explained by body size alone.
    A 4-inch penis on a pygmy is relatively long perhaps, but it’s STILL only 4 inches long — size-standardized schlong length just doesn’t measure up!

    You want a longer penis, then cut the suspensory and fundiform ligaments of the penis — and pull. Surgeons get lotsa $$ for this “augmentation” procedure.

    • Kevin
      Posted March 21, 2011 at 2:22 pm | Permalink

      Oh no. Not even. I mean…no. Just…no.

  24. Torbjörn Larsson, OM
    Posted March 21, 2011 at 3:42 pm | Permalink

    Ha, US and Russia.

    Now I understand the Cold War posturing!? [Which btw then is a somewhat ironic label.]

  25. Posted March 21, 2011 at 4:12 pm | Permalink

    Regarding the “Wow Willy” my only comment is “Nice box!”

  26. Kudu
    Posted March 21, 2011 at 4:39 pm | Permalink

    Ok, so anacondas come from South America and silkworms come from China?

  27. SaintStephen
    Posted March 21, 2011 at 4:42 pm | Permalink

    This post convinced me that I don’t know dick. Ahem.

    What a hilarious biological offering from the mercurial Professor Coyne. I did the classic double-take when I read the title.

  28. Posted March 21, 2011 at 5:19 pm | Permalink

    On one forum I visit the most aggressive, militaristic and argumentative are the Americans. I’ve just started a topic asking if any one is overcompensating. I’m wondering if I will get a 3 day Dawghousing for upsetting people.

    • Veronica Abbass
      Posted March 21, 2011 at 5:54 pm | Permalink

      Please post the name of the forum, so we can follow the discussion.

  29. Adam M.
    Posted March 21, 2011 at 5:55 pm | Permalink

    Seems the author seems to be injecting a value judgment with his choice of coloration… 😛

  30. Lee
    Posted March 21, 2011 at 6:50 pm | Permalink

    Do you think the question “why does penis size differ?” can be answered by asking “why does body sizes differ?”?

    Is the premise behind that second question even true? I’m just thinking of Asians vs. Everyone Else. I don’t have numbers ready at hand but Asians are on average much shorter than everyone else, no? Penis size should follow suit.

    I guess it’s hard for me to imagine an evolutionary influence acting on the penis alone. Is that obvious?

    • Kudu
      Posted March 21, 2011 at 7:03 pm | Permalink

      Umm.. Sexual selection?

      • Sigmund
        Posted March 22, 2011 at 2:59 am | Permalink

        The data (if we can really believe it) suggest little in the way of positive selection and fits a genetic drift model best.
        I had wondered whether there might be a model where initial sexual selection was present but was replaced by genetic drift (for instance if sexual selection takes place in societies where there is a lack of clothing but the expansion of humans wearing clothing ‘covers up’ the opportunity for such selection) however the melanesian results from the island of Papua New Guinea argues against this model.

    • bric
      Posted March 22, 2011 at 2:17 am | Permalink

      As a gay man with considerable, um, anecdotal experience in this area I would have to say there seems to be very little correlation between height and penile size. Weight is another matter – abdominal fat hides the root of the penis and reduces apparent length.
      It is my understanding that average height in a population varies historically with nutrition and health, and it is my impression that this applies to penis size as well: but this is purely unscientific fieldwork. (I don’t recommend a Google search ion this subject)

      • Lee
        Posted March 22, 2011 at 11:49 am | Permalink

        Places like Japan and more recently S.Korea have had their standards of living rise precipitously since the middle of the 20th century. It’s my understanding that the concomitant rise in nutrition and health drove a rise in average height as well. Yet, average height is still below those of Europeans, no?

        How about penis size? Would you be willing to travel the Orient for some coital research?

        • bric
          Posted March 22, 2011 at 1:36 pm | Permalink

          I would like few things better ;). I have done some purely amateur and ad hoc investigations in China, Hong Kong, Japan, Taiwan which bear out the remarks on average penile size above. It is not unusual now to meet Chinese or Japanese men 6 feet or more tall, invariably young; and this is reflected in the other areas of interest but not necessarily in the same chap. There is of course as in all groups a great deal of individual variation, personally I am more interested in aesthetics than size, but one does notice these things.

          • Lee
            Posted March 22, 2011 at 3:15 pm | Permalink

            Well traveled, well traveled.

  31. stvs
    Posted March 21, 2011 at 6:56 pm | Permalink

    No one has posted this gag yet? Really?

  32. abadidea
    Posted March 21, 2011 at 9:11 pm | Permalink

    I understand why it’d be hard to get a large data set from some of those countries, but Saudi Arabia? Is it a religio-cultural hangup?

    • Michael Fisher
      Posted March 22, 2011 at 4:52 am | Permalink

      a large, hard data set ?

  33. Posted March 22, 2011 at 12:47 am | Permalink

    Finally this makes sense to me:

  34. aschlin mouton
    Posted September 12, 2011 at 2:26 pm | Permalink

    how do u talk to ur ancestors to do for u penis-enlargement?

  35. Ken Kukec
    Posted January 2, 2012 at 4:27 pm | Permalink

    Prof. Coyne –

    Given the anxiety that discussions about members can engender among members of our gender, this might be an appropriate time for one of your musical interludes — maybe Maria Muldaur song … you know the one.

    • Ken Kukec
      Posted January 2, 2012 at 5:03 pm | Permalink

      Sorry. I picked up this thread from the “most popular” post on 1/2/12. By the time I got to the end of the comments, I had forgotten that it was three and a half months old. Never mind.

  36. D.Fredrickson
    Posted May 12, 2012 at 7:48 pm | Permalink

    When I credit my dear wife as authority in this matter, I seem to engender unseemly responses among my male acquaintances; why should this be?

  37. D.Fredrickson
    Posted May 12, 2012 at 8:20 pm | Permalink

    Well i should think that a data field of of 100 samples should provide a fairly respectable bell curve of general interest for serious consideation, or at least provide a core basis for future expansion, wouldn’t you think?

5 Trackbacks/Pingbacks

  1. […] map from the Why Evolution is True Blog. Totally. Made. My. Day. Thanks to scicurious for pointing me toward […]

  2. […] if that wasn’t bad enough, the Canadians apparently beat us in another department as […]

  3. […] In light of all the hits I got from Facebook when I said Canadians believe their large penises evolved via natural selection, I figured I would capitalize on that interest and make this post about geographic variation in human penis size. […]

  4. […] wonder about how penis size varies by geography?  Here’s a map.  Yes, I totally used this in my stats […]

  5. […] Geographic variation in human penis size « Why Evolution Is TrueMar 21, 2011 … Posted March 21, 2011 at 4:21 pm | Permalink. Which is odd since the Hungarians are supposed to have ridden in from the East where penises … […]

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