Every Friday on the blog, I answer people’s questions about sex, love, and relationships. This week’s question comes from a reader who wanted to know the following:

“I’ve always heard that you can tell how big a guy’s penis is by looking at other parts of his body, like the size of his feet. Is this true?”

Great question! I have heard a lot of people say things like this too (e.g., that a man's penis length is approximately one-half of his shoe size). So what has the research in this area found? In a 2002 study, researchers collected data on shoe size and penis size from 104 male patients who visited a urologist’s office in the United Kingdom [1]. To ensure accuracy, physicians performed all of the penile measurements (perhaps not surprisingly, when guys measure their own penises, they tend to overestimate). Specifically, doctors measured the length of each man’s flaccid penis while it was fully stretched (this was done in order to approximate erect size). Although there was quite a bit of variability in both shoe size (which ranged from 5.5 to 13 in European sizes) and penis length (which ranged from 6-18 cm, or 2.4-7.1 inches), there was no correlation between them. In other words, the size of a man’s feet revealed nothing about the length of his penis.

So, there doesn’t seem to be anything to that idea. However, it might interest you to know that research has found that penis size is related to other male physical characteristics. For instance, a different study found that finger length ratios are associated with penis length [2]. Specifically, the shorter a man’s index finger is relative to his ring finger, the longer his penis tends to be. Why is that? Both of these factors are thought to be related to early exposure to high levels of testosterone (for more on this study, see here).

Other research has found that penis size is positively correlated with a man’s height and negatively correlated with his weight [3]. This tells us that taller and skinnier guys tend to be more well-endowed.

As you can see, although research doesn't back up the idea that penis size and shoe size are related, there are several other physical characteristics that may hint at a man’s endowment. However, please keep in mind none of these factors (i.e., height, weight, and finger lengths) are reliable indicators of penis size in all cases--we're only talking about general trends here. For example, there are plenty of short guys with larger penises and a lot of tall guys with smaller penises. In other words, appearances can be deceiving.

For previous editions of Sex Question Friday, click here. To send in a question for a future edition, click here.

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[1] Shah, J., & Christopher, N. (2002). Can shoe size predict penile length? British Journal of Urology International, 90, 586.

[2] Choi, I. H., Kim, K. H., Jung, H., Yoon, S. J., Kim, S. W., & Kim, T. B. (2011). Second to fourth digit ratio: A predictor of adult penile length. Asian Journal of Andrology, 13, 710-714.

[3] Ponchietti, R., Mondaini, N., Massimiliano, B., Di Loro, F., Biscioni, S., & Masieri, L. (2001). Penile length and circumference: A study on 3,300 young Italian males. European Urology, 39, 183–186.

Image Source: iStockphoto

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