What is the average erect penis girth according to medical studies?

1. What the big reviews say: pooled means near 11.7–11.9 cm

Two recent comprehensive syntheses that included studies where a health professional measured participants produced very similar values: the 2015 systematic review and meta-analyses report an average erect circumference (girth) of 11.66 cm (4.59 in) (measured samples) ^{[1] [5]}, while a later review/meta-analysis that pooled studies through February 2024 reports an erect circumference mean of 11.91 cm (SE 0.18 cm) based on 5,168 measured erections ^{[2] [3]}. Both papers explicitly emphasize these are pooled averages from studies that attempted standardized measurements ^{[1] [2]}.

2. Single-study results and consistency with pooled estimates

Large single-sample studies show results in the same neighborhood but can differ because of method and sample. An internet-based U.S. study where men self-measured (for condom sizing) reported a mean erect circumference of 12.23 cm ^[4]. Smaller clinical datasets used in nomogram construction reported an erect circumference mean of 11.66 cm (SD 1.10 cm) in their measured sample (n = 381 for erect circumference in that review) ^[5]. These figures align with meta-analytic means, showing modest variation by study type ^{[4] [5]}.

3. Why numbers differ: measurement method, selection bias, geography

Studies that rely on self-measurement almost always report larger averages than those measured by clinicians; the systematic reviews note that volunteer and self-report bias inflate means ^{[1] [3]}. The 2024 meta-analysis also found geographic variation across WHO regions and considerable heterogeneity across studies, meaning regional and sampling differences alter pooled estimates ^{[2] [3]}. Authors caution that measurement technique (location on shaft, whether pre-pubic fat pad is compressed) changes values and explains some between-study dispersion ^{[1] [2]}.

4. Sample sizes and statistical confidence — how precise are these averages?

The pooled erect-circumference estimates come from thousands of measurements (e.g., n ≈ 5,168 in the 2024 review and n = 381 to several thousand in other pooled datasets), giving narrow standard errors in meta-analyses ^{[2] [5]}. Still, the reviews flag moderate-to-high heterogeneity and differing study quality; that heterogeneity means the pooled mean is a useful central estimate but not a precise prediction for any individual ^{[2] [3]}.

5. Practical interpretation: what “average” means for individuals

The reported mean girth of ~11.7–11.9 cm describes a population average; individual variation is substantial (standard deviations reported in some studies are around 1.1 cm for measured erect circumference) ^[5]. Reviews and clinicians emphasize that a majority of men worry about size despite measured values clustering in a narrow range; volunteer bias may push self-selected samples upward, so clinically measured averages are generally lower than self-reported ones ^{[6] [1]}.

6. Competing perspectives and limitations in the record

Sources agree that measured erect girth centers near 11.6–11.9 cm but disagree on the extent of geographic variation and the contribution of measurement protocol to heterogeneity ^{[2] [3]}. Available sources explicitly warn about volunteer bias and methodological inconsistency; they also call for standardized measurement protocols and region-specific norms to improve precision ^{[1] [3]}. Available sources do not mention newer post-2024 large population studies outside the included meta-analyses.

7. Takeaway for readers and clinicians

If you need a concise answer grounded in measured clinical research: expect an average erect girth of roughly 11.7–11.9 cm (about 4.6–4.7 in) based on pooled, clinician-measured studies involving several thousand men ^{[1] [2] [3]}. Clinicians and researchers urge interpreting that mean within the context of measurement method, sample selection, and regional variation ^{[2] [3]}.