Sunday, June 9, 2013

New penis survey from TheyFit: One size does NOT fit all!

Theyfit condoms reveal the largest, most accurate penis size survey data ever gathered.

You will most certainly be happy to discover how consistent these data are with the ones already gathered in this post, in this one, and in this one as well.

An anonymous sample of over 20,000 men shows that the UK ‘normal’ [size] is not 6 inches – it is nearly a whole inch less!
And whilst length is commonly the ‘measure of a man’, girth should not be overlooked as the survey reveals a staggering 4 inches difference when it comes to the circumference of the smallest and largest.

  • Average length is 5.1” (13cm), ranging from less than 3” up to more than 10”.
    • 26% of male population is less than 5" in Length,
    • 53% is between 5" and 6" in Length,
    • 21% is longer than 6" in Length.
  • Average circumference is 4.7” (12cm), with condom widths that fit girths of 3.5” up to 7.5”.

TheyFit’s size database was compiled by converting its unique "FitKit" measurements into metric sizes.
The FitKit provides each user with a randomised size code such as M17 or S77, so it’s not immediately obvious if someone needs a large or small condom.

Joe Nelson, founder of Theyfit comments, “Our anonymous data represent the most accurate survey of penis sizes ever collected. Previous studies have relied on self-reported measurements from men, leading to an issue of ‘size exaggeration’. But men buying our condoms are much less likely to do this for 2 reasons – firstly because they are parting with money for a custom fit condom and secondly because of our patented randomised size code system (rather than labels like small, medium and large), there’s simply less focus on whether someone is bigger or smaller – it’s all about getting a custom fit.”

I managed to get in touch with Joe Nelson himself, and he kindly answered to some of my further questions:

  • Was the circumference distribution normal (I believe you have less activity for standard sizes than for small or big sizes)?
Joe: Yes, quite a wide distribution. On the contrary, some of our happiest customers, based on feedback, are guys who have a nominal width requirement of 53 or 55mm, but love the fact that TheyFit are the correct length for them. Because we don’t market as “the condom for big or small guys” but instead as “the great condom for every guy” then I think this explains why guys of all sizes come to us, and enjoy us. Fact is, traditional condoms don’t fit nearly all guys, owing to being at least 7” long (but usually 205mm or 8.1”). 11 clinical studies dating back to 1993 identify fitting issues that 40-45% of guys experience, and they all think the number might be too low as many men don’t realise “it doesn’t fit” is even a valid complaint.

  • What is the standard deviation for circumference?
Joe: The s.d for nominal width was 6.4mm i.e 12.8mm circumference so almost exactly half an inch. We assume an average 18% latex stretch for optimum comfort, so you can expand it to circumference using that.

  • How did you build your data from numbers to cm (or in)?
Joe: [I] took a mid point for each letter/number. The critical part for accuracy is that the guys measuring are more likely to be honest. The midpoint methodology will cancel itself out over a large sample set like ours, from a mathematical perspective.

From all these information, we can draw some fair conclusions:
  • Average erect penis girth: 120mm +-15.1mm (4.7in +-0.59in)
  • Average erect penis length (do not press the pubic bone with your ruler): 130mm (5.1in).
  • About 10 to 20% condom stretch is tolerable for most guys (18% being the optimum for comfort with TheyFit comdoms), and above 25%, you are going to have a bad time. It's likely going to feel much too tight for you at the base.
  • Generally speaking, with store-bought condoms, above 135mm (5.3in) circumference you are going to be having issues with tightness and below 115mm (4.5in) a normal condom will likely be too loose and slip or fall off. 


TheyFit - Reddit FAQ

TheyFit - National condom day

The Inaugural TheyFit UK Size Study Survey


  1. Did you see the measurement methodology though? It's from the underside. Thats not the way studies measure.

  2. Excuse me? The "FitKit" that you reference in this, is a printout on their website.

    This is the printout

    It very clearly tells the user of the kit to measure from the other side.

    1. Well, it is written:
      To find your length; place the template alongside your firm erection
      with the bold base line as far as the condom would unroll on the underside.
      Your length is shown by the letter at the tip of your penis.

      Maybe it is just a "typo" in the image and I'm sure many take the measurement from the up side...
      The underside is anyway known to overestimate the penis size.
      And the difference is not so important and who cares of a few mm or even a cm difference?

  3. I got no idea how you guys are put together, but the balls or the turkey neck is the limiting factor, and measures far shorter than from above. If you want a large measurement, the only way is to measure past your scrotum from the underside.

  4. IHaveANameThisIsn'tItJune 18, 2013 at 7:22 PM

    I believe 5.1" (13cm) underestimates average penis length. Consider a statistic Joe cites: "traditional condoms don’t fit nearly all guys, owing to being at least 7” long (but usually 205mm or 8.1”)."

    So a man with a long penis fits fine in traditional condoms. Therefore, he is less likely to seek out custom fitted condoms than a man who finds himself with several inches of latex bunched up at the base of his penis.

    I think it's reasonable to infer, then, that men with longer penises are underrepresented in TheyFit's data.

    1. There are plenty of reddit pages where Joe Nelson explains in-depth what its customer base is, what the condom industry is about, and why he believes he has a fairly good representative sample of the population...

      Anyway, you can not dismiss facts with inferences from beliefs and likelihood (from your own point of view).

      Facts here are:
      - scientific studies
      - surveys from professionals
      Where are your elements of proof?

    2. IHaveANameThisIsntItJune 21, 2013 at 12:18 AM

      I don’t deny the scientific rigour of TheyFit’s study. I am simply saying that their data is composed exclusively of men who have decided to buy custom-fitted condoms.

      This means there’s self-selection bias. We must then ask, why do some men decide to buy custom-fitted condoms, and others don’t?

      Some men, after all, have perfectly good experiences with regular store-bought condoms. Considering regular condoms are cheaper and more widely available than custom-fitted condoms, these men have little motivation to buy from TheyFit.

      Men who don’t fit regular condoms are far more motivated to buy custom-fitted condoms. Therefore, their measurements are far more likely to end up in TheyFit’s database.

      Condoms can fit badly because they’re too loose, too tight, too long, or too short. I concede it’s merely my point of view that, of these four possibilities, being too short is the least likely reason for a condom to fit badly.

      But I’m not the only one with this point of view:

      “The irony is, if you know someone who uses a Magnum condom, the one thing they are unlikely to have is a HUGE PENIS. Sure, they might have a long one (but then, regular condoms are usually 7 or 8 inches long, so that’s not a reason to buy a specific condom).”

      That quote is from If your penis is long, any regular condom will do. It’s when your penis is short or thick or thin that regular condoms get on your nerves and you need to seek out a more specific size.

      I am not dismissing any facts. What we have here are not facts, but statistics. A statistic can only be elevated to the hallowed level of fact when we view it in its proper context.

      I am merely trying to help elucidate the context of these statistics.

      (The context of self-selection also suggests other things about TheyFit’s data. Not only do I believe their finding for average length is deflated, I also believe their standard deviations for length and girth are likely higher than what you would find in a more representative sample.)

    3. Well I believe you spend a lot of energy for few mm difference ;-).

      Two points:
      1- The question of sample quality is partially answered by Joe Nelson above:

      Was the circumference distribution normal (I believe you have less activity for standard sizes than for small or big sizes)?

      Joe: Yes, quite a wide distribution. On the contrary, some of our happiest customers, based on feedback, are guys who have a nominal width requirement of 53 or 55mm, but love the fact that TheyFit are the correct length for them.

      2- Imperfects statistics may become facts when taken from different sources, using different methods but basically reaching the same conclusions
      - theyfit girth is 120mm from self-selected sample, by choosing a proper condom fit.
      - Wessells girth is 123mm from a sample scientifically chosen in an hospital, by using drug injection and measured by staff.
      - Janssen girth is 122mm from a sample of men who have responded to an announce in a newspaper, who have been trained and have self reported their girth, thanks to a dedicated tool during visual and self-stimulation.
      - Da Ros girth is 119mm,scientific sample, pharmacological erection and measurement by staff.
      - Promodu girth is 115mm (self report and then staff measurement on a control sample)

      Same goes for length:
      - TheyFit length is 130mm (NBP)
      - Wessels length is 129mm (NBP)
      - Promodu length is 129mm (NBP)

  5. it's obvious that the fact that a regular condom DO NOT roll all the way down the shaft IS pissing off a lot of people..i could think of so many reasons why it's pissing off people..
    also there could be some who could use that trick of having a special condom which COULD roll all the way down just to give out the illusion a mate to have a longer penis..since it's all about visual to some especially women when it comes to being impressed by something..
    so it could explain why people are buying average length condoms for their average penises...

    also about the unusually large GIRTH listed in their database it could be that some kinky people are using condoms and lubes for something else like using objects or fists/feet etc...there is a pretty large and renowned to not say famous kinky/bdsm community in th UK that's a fact..

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