Where the tape goes.
Three conventions decide what every figure in this app means: where a length starts, what path it follows, and where a circumference is taken. None of them is the only reasonable choice, and each one differs from advice you may have been given elsewhere. They are written down here because a figure taken under one convention and compared against a figure taken under another is not a comparison, and nothing in the app can tell the difference once a number has been typed in.
Read in
The diagrams on this page are schematic: they show where a tape starts and what path it follows, not how big anything is. The comparison drawings are the ones drawn to scale.
Length is the straight line
From the centre of the ring where the shaft leaves the body, to the point on the shaft furthest away from it, in a straight line.
It is a point-to-point distance rather than a path over a surface, which is what a ruler held against the body reports and what this app's own tape reads off the mesh. It has one consequence worth knowing before you type a figure in: on a shaft that curves, a straight line is shorter than the surface it spans, and it keeps getting shorter as the curve increases. That is the behaviour this app wants. A figure that follows the bend does not move with the bend at all.
Girth is taken halfway along
The distance around the shaft on a plane halfway along it, measured the way a tape lies rather than the way skin folds.
Halfway is measured along the shaft itself, not along the straight line the length reports, so the plane follows a bend instead of cutting across it. The figure is the perimeter of the smallest convex outline containing that cross-section, which is what a tape pulled snug traces: it bridges a hollow rather than dipping into it. There is no landmark in a circumference — a tape around the shaft has no pubic bone in it — so nothing is ever added to or taken off a girth anywhere in this app.
The tape starts at the skin
Where the shaft meets the body, at the surface. Nothing is pressed in.
This is the single convention most likely to disagree with a figure somebody arrives with, because the published series this app compares an erect length against were read the other way — with the ruler pushed through the pubic fat pad until it stops at the bone. Those are two different starting points on one body, so the comparison moves the published mean by a stated amount rather than pretending they agree. The amount is printed below, in whichever units you are reading in, and it is the only difference on this page that this app converts.
The offset is 0.71 in, taken off erect length only. It moves the published mean before a reading is placed in the distribution. It is never added to or taken off a member's own reading, and never applied to a circumference, which has no such landmark in it.
It is derived rather than read off a paper: no published series reports the gap as a statistic of its own. The series it was derived from are named at the foot of this page.
A bend is an angle, and up is positive
The angle between the direction the shaft leaves the body in and the direction it points at the far end. Upward is positive, downward negative.
It is read off the centreline rather than off the straight line the length reports, because a straight line from base to tip has already averaged the whole bend into one direction, and it under-reports a shaft that runs straight and then turns. The neutral position of the control is not the same thing as straight: the model carries a bow of its own, and the readout says what the measured angle is rather than what the slider was set to.
The sac is two ruler numbers
How wide it is at the widest point, and how far the lowest point hangs below the ring where the shaft leaves the body.
The drop is measured against gravity rather than along the shaft, because hanging is defined against gravity — taken along the shaft it would shrink whenever an erection raised the shaft, which would be a number about the wrong thing. Only what hangs below that ring counts, so the skirt where the shape meets the body is never mistaken for the sac. Both are one pair for a figure rather than one pair per state: the body has one answer.
What these figures are not
Each of these is a real way to measure, and each one produces a number that is correct for what it measures. None of them is what this app means. Exactly one of them has a derivation behind it, so exactly one of them is converted; the rest are stated and left alone, because a conversion nobody derived is a made-up number.
Pressed to the bone
- Elsewhere
- The ruler pushed into the pubic fat pad until it stops against the bone, so the reading includes whatever the pad covers.
- Here
- The tape starts at the surface, where a ruler held against the body starts, and where this app's own tape reads off the mesh.
This is the one difference on this page with a derivation behind it, so it is the one this app acts on. The published means it compares an erect length against are read to the bone, so a stated offset comes off the mean before a reading taken at the skin is placed in the distribution. It is applied to the published figure and never to a member's reading, and never to a circumference.
Converted: a stated offset comes off the published mean.
Following the curve
- Elsewhere
- A tape or a piece of string laid along the shaft so that it follows the bend, or a figure taken as the average of the outer and the inner curve.
- Here
- A straight line from the base to the furthest point, which shortens as the bend increases.
A path laid along the surface is unchanged by the bend in this app's own model, by construction, so a length measured that way would ignore the curvature entirely and read the same on a straight shaft as on a strongly curved one. This app holds no figure for how far the two differ on a real body, so nothing converts between them: a figure taken along the curve is a different measurement rather than this one made larger.
Not converted: the difference is stated and nothing is adjusted.
Along the underside
- Elsewhere
- The tape run along the underside of the shaft rather than over the top.
- Here
- Neither. The length is a distance to the furthest point, wherever that point lies, so it names no side to travel along.
A different path over a different surface. This app holds no figure for the gap between them and invents none.
Not converted: the difference is stated and nothing is adjusted.
Around the base
- Elsewhere
- The tape at the base of the shaft rather than halfway along it.
- Here
- Halfway along.
Two places on one shaft, and a figure taken at one is not a figure taken at the other. The study bank records where a paper put its tape for exactly this reason and refuses to pool figures taken in different places, and nothing here converts one into the other either.
Not converted: the difference is stated and nothing is adjusted.
Around the thickest point
- Elsewhere
- The tape wherever the shaft is widest.
- Here
- Halfway along, wherever that happens to fall.
A maximum and a midpoint answer different questions, and a maximum cannot be smaller than the figure at any one plane. Entered as a midpoint it reads larger than the tape here would have reported, and once it has been typed in nothing can tell the two apart.
Not converted: the difference is stated and nothing is adjusted.
Stretched
- Elsewhere
- A flaccid shaft drawn out to its limit, which the study bank carries as a dimension of its own.
- Here
- Two states, at rest and erect. Nothing here is pulled.
No surface in this app places a member's reading in the stretched distribution, so a stretched figure typed into an erect box is a third measurement in a box built for one of two, compared as though it were one of them.
Not converted: the difference is stated and nothing is adjusted.
If you are typing a figure in
- Measure the way this page describes, or know that you have not. There is no field on the form for which convention a number was taken under, and nothing in the app can work it out afterwards.
- A typed figure is compared against figures taped off a mesh under these rules, and against published distributions that state their own. The comparison is only ever as good as the agreement between the three.
- A figure taken to the bone is not the figure this app would have taped, and the app cannot tell that it was. The gap between the two starting points is stated below; what this app does with that gap is move a published mean, never somebody's own reading.
- The comparison drawings are drawn from these numbers. A figure typed under a different convention does not draw wrong — it draws exactly what it says, which is why the difference matters.
There is one way to put something anchored on the record: the printed validation card , which supplies a real scale from a standard object in the same photograph. A pass is recorded against your account and puts a mark beside your name that this site established rather than you chose. It does not change any figure here: the readings this site ranks are taped off your modelled body, and a card cannot reach them.
Where these came from
The conventions on this page are decisions this project made and wrote down, not findings. The one figure on it that is not a decision is the offset between the two starting points, and that figure is derived rather than read off a paper: no published series reports the gap as a statistic of its own, so it comes from clinician series that measured both starting points in the same men. Those series, their sample sizes and their measured gaps are named below and again on the statistics page, beside every distribution the offset is applied to.
- Habous 2015, 778 men — a gap of 0.71 in. Both landmarks taken in the same men, in one clinician series.
- Habous 2018, 201 men — a gap of 0.76 in. The same pair of landmarks in the same men, in a second series.
Salama 2018 reports a far larger gap and is not used. Its non-bone-pressed mean sits far below every other series in this bank, so what is unusual about it is where that series started the tape rather than how much the fat pad adds. A gap that large is not the same measurement done twice.
Neither series was read off its own paper: both figures were transcribed by somebody else. This app refuses figures of that class as distributions — none of them is a curve any reading is placed in — and spends these two only as the stated assumption above, which is why the offset carries no citation of its own. It adjusts a comparison; it does not join the data.
- Flaccid length — the paper does not say where its ruler started, so nothing can be matched and nothing is adjusted.
- Stretched length — measured to the bone, so the offset above comes off its published average before a reading is placed in it.
- Erect length — measured to the bone, so the offset above comes off its published average before a reading is placed in it.
- Flaccid circumference — a circumference has no starting landmark, so there is nothing for the two to disagree about.
- Erect circumference — a circumference has no starting landmark, so there is nothing for the two to disagree about.
Every distribution this app compares a reading against, with its sample size, its method and its citation, is on the numbers behind the sizes .