Method
Three places to take girth
Girth at the base, at midshaft and around the glans are three different numbers; the convention is midshaft and the other two need labelling.
Guides on Method: Bone-pressed length, start to finish, Stretched flaccid length, and why the clinics take it, Girth, done the way the studies do it, The measurement glossary
Base, midshaft and glans girth are three different numbers, sometimes more than a centimetre apart on the same person, and midshaft is the usual convention for comparison. Published studies do not all use the same site, so "girth" without a site attached is not one number.
What each site captures
Base girth is taken where the shaft meets the body. It is the least standardised of the three sites, because the exact starting point is soft to define and the reading is easily inflated by including tissue that is really the fat pad rather than the shaft. It tends to run larger for men whose shaft thickens toward the body, and it is the site most likely to be quietly substituted for midshaft by someone who prefers the bigger number.
Midshaft girth is taken halfway between the base and the corona - the ridge at the base of the glans. This is the convention. It is the site most measurement protocols specify, and the one a percentile you look up most likely assumes. It is not universal, though: Chen and colleagues (2000), International Journal of Impotence Research, measured circumference at the base and at the tip in 55 patients, and a condom study by Smith et al. (1998) reported a self-measured mean basal circumference of 13.19 cm. Finding it reliably is a short, separate task, because "halfway" only means something once you have fixed both ends.
Glans girth is taken around the head, usually at its widest point. It behaves differently from the two shaft measurements: it is shaped by the glans rather than the shaft, it does not track shaft girth closely from person to person, and clinical data on it are much thinner than for midshaft. Some men measure larger here, some smaller, and there is no reliable rule for which.
Why midshaft won
Not because it is the largest or the most flattering number - on many men it is neither. It is the convention because a point defined as halfway between two anatomical landmarks is reproducible: measure it twice and you land on the same site both times, on yourself and on someone else. Base girth drifts because its starting landmark is soft. Glans girth measures a different structure with different biology. Midshaft is also where the shaft actually tends to be narrowest for a lot of men, which surprises people expecting the reported figure to be their largest reading.
| Site | What it captures | Reproducibility | In the pooled literature |
|---|---|---|---|
| Base | Shaft near the body, often includes fat pad | Low - landmark is soft | Used by some studies |
| Midshaft | Shaft at its defined midpoint | High - fixed landmark | The reference figure |
| Glans | Head, not shaft | Moderate | Sparse, separate biology |
The comparison people actually want to make
Someone who measured at the base and is comparing the result to a midshaft percentile is not comparing like with like, and the gap between the two numbers has nothing to do with where they sit against other men. The same goes for a glans reading held up against a shaft percentile chart - the two structures were never claimed to be the same thing. This is a narrower version of a mistake that runs through the whole subject: a number without its conditions attached is not comparable to anything, and site is one of those conditions along with state, tension and instrument.
None of this is an argument for choosing whichever site reads largest. It is an argument for writing the site down next to the number, every time, so that a reading taken today can be checked against one taken in six months, or against a published figure, without the comparison being silently wrong.
What this has nothing to do with
A tape around three sites still produces a length in centimetres, and nothing about site selection turns that into a judgement of how the whole thing looks together, which is a separate kind of question a person or an image model can answer and a ruler cannot - Rate Penis covers that kind of subjective read directly. An AI system trying to estimate proportion from a photograph faces the same site-ambiguity problem from the other direction: it cannot know which site a viewer's eye lands on, which is one of several reasons an image model's accuracy on this kind of estimate is limited in ways that are geometric rather than a training problem. And a photo-based rating, built around what a picture actually conveys rather than a circumference, is measuring something else again - proportion and presentation, not millimetres at a defined site. None of those are a substitute for a tape at midshaft, and a tape at midshaft is not a substitute for them; a subjective score from somewhere like Rate Cock answers a different question than the one this site answers, and mixing the two up is where most of the internet's arguments about size actually come from.