What percentile is a 5.5‑inch erect girth based on measured population studies?

1. What the primary studies actually measured

Large systematic reviews of professionally measured data report mean erect circumference values clustered around about 11.6–11.9 cm (4.6–4.7 inches): the frequently cited 2015 review reports an average erect circumference of 11.66 cm (4.59 in) (measured by staff) ^[1], while a broader meta‑analysis that pooled many studies found a mean erect circumference of 11.91 cm ^[2]. Those figures establish the best available measured central tendency for erect girth in clinical research, not the tail probabilities.

2. Why a single percentile isn’t directly extractable from the papers

The meta‑analyses report means and standard errors but do not publish a single pooled standard deviation or a verified cumulative distribution for girth that would let one compute an exact percentile for any given measurement; authors explicitly note heterogeneity across regions and methodological differences and caution against overgeneralizing regional samples to a global distribution ^[2]. Without a reported pooled SD or percentile table in the provided sources, any numeric percentile must be characterized as an estimate rather than a precise statistical fact.

3. Translating 5.5 inches (≈14.0 cm) into a practical sense of rarity

Relative to the measured means above, 14.0 cm is ~2.1–2.3 cm larger than the reported mean erect circumference figures (11.66–11.91 cm), which places it clearly above the median and likely into the higher percentiles; independent online calculators and pooled‑data visualizers built from public study results (e.g., calcSD) are commonly used to map sizes to percentiles and generally indicate that a ~14 cm girth lies in the upper part of the distribution, often reported informally in the roughly 80th–95th percentile range depending on assumptions about dispersion ^{[3] [4]}.

4. Sources of uncertainty that widen the plausible percentile range

Measurement technique (base vs mid‑shaft circumference), whether measurements were bone‑pressed for length analogues, volunteer self‑selection, small regional sample sizes and true biological variation all push percentile estimates in different directions—systematic reviews flag moderate heterogeneity and potential bias in available studies, meaning the same numeric girth can correspond to different percentiles in different datasets ^{[2] [1]}. In short, plausible percentiles for 14.0 cm vary because the underlying datasets are not perfectly harmonized.

5. Responsible, evidence‑based answer

Given measured-study means (11.66–11.91 cm) from the literature, and acknowledging the absence of a pooled SD or published percentile table in these sources, the best evidence‑based statement is: a 5.5‑inch (≈14.0 cm) erect girth is above average and most likely falls somewhere in the upper quartile to upper decile of men (roughly the 75th–95th percentile), with the precise percentile dependent on which study population and dispersion estimate is used ^{[1] [2] [3]}. This expresses the directional certainty (above average) while honestly reflecting statistical uncertainty in the sources.

6. What would tighten the estimate—and why it matters

A tighter percentile would require access to raw, measured‑participant data or a published pooled standard deviation for erect girth from representative, professionally measured cohorts; regional breakdowns would also matter because the meta‑analysis documents geographic heterogeneity ^[2]. For practical use—condom sizing, clinical counseling or personal curiosity—treat 14.0 cm as unambiguously larger than typical measured averages but avoid claims of an exact percentile without a documented dispersion parameter.