How to measure the way the research does

Almost every argument about size online is two people comparing measurements taken different ways. The published literature uses one method, consistently, and it is the only one that lets your number mean anything next to anybody else's.

Length: bone-pressed, from above

Stand up. Press the ruler firmly into the pubic bone at the base, above the shaft, until it stops against bone. Read at the tip.

Three details decide whether the number is comparable:

Press hard. The fat pad above the pubic bone compresses, and how much it compresses varies enormously between people. Not pressing is the single largest source of difference between a self-measurement and a clinical one, and it is why bone-pressed is the standard - it removes a variable that has nothing to do with the thing being measured.

Measure along the top. The dorsal surface, base to tip. The underside follows a longer path and gives a larger number that is not comparable to anything published.

Keep the ruler parallel. Angled down or up along the shaft adds length that is an artefact of the angle.

Take three readings and use the median. If they spread by more than about half a centimetre, something in your technique is varying - usually the pressure.

Girth: circumference, at the midpoint

A flexible tape, wrapped around the shaft at the midpoint, snug but not compressing.

Girth is a circumference, not a width. This confusion is common and produces numbers that are roughly a third of what people expect, because width is the diameter and circumference is roughly three times it.

If you have no tape, wrap a strip of paper, mark where it overlaps, and lay the strip against a ruler. This is as accurate as a tape and is the method most people already have the materials for - the instrument matters less than most people assume.

Girth varies along the shaft, often substantially. The midpoint is the convention. Measuring at the widest point and calling it "girth" is a different measurement.

State: the part people skip

Erect measurements require full erection, and "mostly" is not a state that produces repeatable numbers. Flaccid measurements are barely worth taking at all - flaccid size varies with temperature, time of day, and recent activity, and correlates poorly with erect size.

The literature also reports stretched flaccid length, which correlates better with erect and is easier to standardise in a clinical setting. If you see a figure that seems high for a flaccid measurement, it is probably stretched flaccid.

Record the method with the number

A measurement without its method is not data. Write down: bone-pressed or not, top or underside, state, and instrument. Six months later this is the difference between a comparison and a guess.

It also matters because the published figures are lower than most people expect, and a large part of the gap is method rather than anatomy - self-reported figures run high for reasons that are well documented.

What this method does not give you

A measurement is a length in centimetres. It is not an assessment, and the two get conflated constantly. If what you actually wanted was a subjective judgement rather than a figure, that is a different kind of number entirely and comes from somewhere like Cock Rate rather than from a ruler - worth being clear with yourself about which one you were after, because they answer different questions and neither substitutes for the other.

And know your error bars. Careful technique gets you to roughly ±0.3 cm on length and ±0.2 cm on girth. Differences smaller than that are noise, and there is more of it than people expect.