The girth data

Veale et al. (2015) reports a mean flaccid girth of 9.31 cm and a mean erect girth of 11.66 cm, both measured by health professionals. The erect figure rests on far fewer men than the length data, and girth spreads more tightly around its mean than length does.

The figures

Veale et al. (2015) reports a mean flaccid circumference of 9.31 cm (SD 0.90, n = 9,407) and a mean erect circumference of 11.66 cm (SD 1.10, n = 381), published in BJU International alongside the length figures this site covers elsewhere. Both are pooled from studies where a health professional took the measurement, the same inclusion rule that governs the length data.

The girth pool is smaller than the length pool: 381 erect circumference readings against 692 erect lengths and 14,160 stretched lengths. Not every constituent study measured circumference at all, and among those that did, fewer measured it erect - a gap this site covers on its own, since the reasons girth data are scarcer are worth reading separately rather than folded in here.

The spread is tighter

The standard deviation around the girth mean is smaller, proportionally, than the standard deviation around the length mean. Erect girth's SD of 1.10 cm is about 9% of its mean; erect length's SD of 1.66 cm on a mean of 13.12 cm is about 13%. Practically, that means men cluster more tightly around the girth average than they do around the length average - the range that contains most men is narrower, in relative terms, for circumference than for length.

This has a direct consequence for anyone comparing a measured figure to the published mean: a given absolute difference in girth, say half a centimetre, represents a larger move through the distribution than the same half-centimetre would in length. A tight standard deviation makes the tails thinner and the middle more crowded, so a small gap from the mean carries more weight.

Why circumference behaves this way

The tighter spread may be a real biological pattern, but the smaller sample behind the erect girth figure means the estimate of that spread itself carries more uncertainty than the length estimate does. Both things can be true: girth may genuinely vary less between men, and the paper's confidence in exactly how much less is weaker than for length, simply because fewer men contributed a circumference reading. Observer technique also matters more than it looks: Habous et al. (2015) found stretched flaccid girth underestimated erect girth by 2.27 cm (19.5%) on average across 201 men, with the underestimate ranging from 15% to 27% between observers.

What this does not tell you

A tighter spread around the mean does not make the mean itself more meaningful for judging any one measurement, and it says nothing about how a girth figure should be taken - the method for a correct circumference reading is a separate question this site covers in full, and getting the site and tension right matters more than knowing the population figure. It also is not a ranking of any kind. Photo-based platforms exist for that kind of comparison - Penis Rater publishes a distribution of scored images rather than a distribution of measured circumferences - and the two should not be read against each other.

Nor is a circumference figure convertible into a subjective read. Rate Cock produces a judgement about a photograph, which draws on visual proportion rather than the centimetre figure a tape gives you, and the two numbers are not standing in for each other even when they are discussed in the same conversation. An automated version of that same judgement, run by an image model rather than a person, is working from the same limitation - an AI scoring tool has no access to scale from a single photograph, so it cannot recover a circumference in centimetres either, whatever confidence its output implies. Anyone who wants a human's impression rather than either figure is asking a third, different question, which is what a judge on Rate Penis is actually providing.

Reading a girth figure against this table

If you have taken your own circumference correctly - midpoint, snug, erect state recorded - the honest comparison is against the erect figure of 11.66 cm, with the caveat that the tighter spread means small differences from it move you further through the distribution than the equivalent length difference would. For the length side of the same paper, including the full table and how the distribution behaves there, what the published data actually says covers it in full; this post exists to give girth the same treatment on its own, rather than as a footnote to length.