Method
Bone-pressed or not: the two length numbers
Two legitimate length measurements exist, they differ by a variable amount, and only one of them is comparable to the published data.
There are two different, both legitimate, ways to take an erect length reading, and they do not produce the same number. Confusing them is one of the most common reasons two people's measurements disagree without either of them having measured badly.
Two readings, one shaft
Bone-pressed length, BPEL, is taken with the ruler's end pushed firmly through the tissue at the base until it stops against the pubic bone. Non-bone-pressed length, NBPEL, is taken with the ruler resting on the skin at the base, without that pressure. Both start from the same shaft. They differ only in where, exactly, the ruler's zero end is allowed to sit.
Neither reading is fake, and neither is a mistake in isolation. A clinician might choose NBP because it is faster and requires no explanation to the patient of why the ruler is being pressed into them. The problem is not that either reading is wrong. It is that they answer slightly different questions, and treating them as one number causes real confusion.
Where the gap comes from
Between the pubic bone and the base of the visible shaft sits a layer of tissue that varies in thickness from one person to the next, and in the same person over time. Press through it and that layer drops out of the reading entirely. Rest on top of it and the reading includes whatever that layer measures on the day. What that tissue is and why its thickness varies gets a full answer elsewhere - the point that matters here is narrower: the gap between BP and NBP is exactly that layer's thickness, and it is not the same number twice, even for the same person, because the layer itself is not fixed.
That is also why the gap cannot be stated as a fixed amount. It moves with body composition, with hydration, and with the day. A figure like "NBP always reads a centimetre high" is a claim this site will not make, because the direction is reliable and the magnitude is not.
The comparison
| Bone-pressed (BPEL) | Non-bone-pressed (NBPEL) | |
|---|---|---|
| Reference point | Pubic bone, through the tissue | Skin surface at the base |
| Comparable to the published literature | Yes - the standard method | Only to studies that used the same protocol |
| Sensitive to body composition | No, the tissue is compressed out | Yes, tracks the tissue layer too |
| Speed to take | Slightly slower, needs firm pressure | Faster |
| What varies the reading day to day | Technique consistency | Technique plus tissue thickness |
Which one to report
If the point of taking the measurement is to have a figure that means the same thing as anyone else's, bone-pressed is the one to report. It is the method behind the large pooled datasets this site cites, and a non-bone-pressed figure sitting next to those numbers is not really being compared to them, whatever the two look like side by side. The full bone-pressed protocol, landmark to write-up, is covered step by step separately, including how much pressure is actually needed to reach the bone without unnecessary discomfort.
None of this makes NBP worthless as a number. It is simply a different measurement, useful in its own clinical contexts, and the mistake is only in comparing it to a bone-pressed figure as though the two were interchangeable.
Record both, label both
The practical answer is not to pick a side permanently but to record which one you took, every time. A figure without its method attached is closer to an anecdote than to data, and "length: 14.2 cm" tells a reader nothing about which of these two readings it is. Write bone-pressed or non-bone-pressed next to the number, the same way you would note the state and the instrument, and the ambiguity disappears.
If you are unsure whether you actually reached the bone or stopped short on the tissue in front of it, the landmark itself, and what it feels like when the ruler is genuinely there, is worked through separately.
What neither number is
Both of these are lengths, in centimetres, with a method attached. Neither is a rating, and nothing about choosing correctly between them turns a measurement into a judgement. That distinction gets lost constantly online, where a length in centimetres and a score out of ten from an AI-judged photo site like Rate Cock get discussed as though they were versions of the same fact - they are not, and a ruler pressed to bone is not competing with a photo score, it is answering a different question entirely. The same applies to a human's impression of size from a picture, which Rate Penis is clear is an opinion rather than a figure, to a crowd of scored photographs of the kind Penis Rater collects, and to an app's estimate from an image, which is inference from visual cues rather than a measurement, for reasons that are geometric rather than a software limitation. A tape or ruler, used either way described above, is the only one of these that is actually reporting a distance.