Shoe size

Shoe size does not predict length: when two urologists measured 104 men and compared their stretched length with their shoe size, they found no statistically significant correlation. It is one of the few folk correlates in this subject that has been tested directly, rather than merely repeated.

What was measured

The study is Shah and Christopher (2002), "Can shoe size predict penile length?", BJU International. Two urologists measured the stretched length of 104 men prospectively and related it to each man's shoe size, so the length side was clinical measurement rather than self-report. That design tests the claim on its own terms - the folk belief is about shoe size, and shoe size is what was compared - rather than lining up two separate self-reported surveys after the fact. The median stretched length was 13 cm and the median UK shoe size 9 (European 43), and there was no statistically significant correlation between the two. The authors' conclusion was blunt: the supposed association "has no scientific basis."

Why a direct test matters here

A lot of folk claims in this space never get tested this cleanly - they survive on anecdote, or on studies that measured only one of the two quantities and inferred the rest. The shoe-size claim is an exception: someone actually ran the comparison, on real measurements, in a peer-reviewed setting, and published a negative result. A negative result from a well-designed study is not a weaker finding than a positive one - it is just as informative, and in this case it is the more reliable of the two, given how little support the positive version ever had.

Why the belief survives a null result

Folk beliefs about body correlates rarely die when the literature contradicts them, and this one has some obvious reasons to persist regardless of the evidence. It is a simple, checkable-feeling claim - everyone has a shoe size and can compare it to their own case, which produces confirming anecdotes constantly and disconfirming ones rarely get noticed as disconfirmation rather than exception. It is also repeated in enough casual contexts that it acquires the texture of common knowledge, independent of whether anyone involved has read the study, which is a general pattern with folk statistical claims and not specific to this one.

What this means practically

If you were hoping a shoe size might tell you something, the honest answer from the one study designed to check is that it does not, in any useful way, and there is no reason to treat your own shoe size as evidence about anything else you are wondering about. Height has a weak but real correlation of its own, worth reading for contrast, and finger-ratio research is a separate small literature with its own status - neither should be assumed to behave the way the shoe-size claim does, since each has been tested, or not tested, on its own terms.

None of this touches how a photograph is assessed by an image model or a human judge, which never involves a shoe measurement at all, and it is a different kind of question from what a browsing platform ranks by when it scores photographs against each other. If what you actually want is someone's subjective read rather than a tested correlate from urology literature, a rating service is answering that different question, and shoe size will not be part of its inputs either.