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What does medical research say about average penis length and girth worldwide?
Executive summary
Major medical reviews find the worldwide average erect penis length is about 13.1 cm (≈5.17 in) and average erect circumference about 11.66 cm (≈4.59 in); these figures come from a commonly cited 2015 systematic review of measured (not self‑reported) data [1]. More recent aggregations and meta‑analyses reproduce similar mid‑13 cm estimates for erect length but note wide methodological differences and country‑level variability [2] [3].
1. What the large reviews report: a concise baseline
Systematic reviews that pooled studies with clinician‑measured penises report an average erect length of roughly 13.1 cm (5.1–5.2 in) and an average erect girth (circumference) near 11.66 cm (4.59 in) [1]. Science magazine’s summary and patient‑facing sites such as Verywell Health echo those central numbers, noting the measurement technique (pubic bone to tip, compressing fat pad) used in the studies [4] [5].
2. Why different sources show different “world averages”
Not all datasets are created equal: some sites and recent compilations combine self‑reported surveys, corrected self‑reports, smaller country studies, or meta‑analyses that include stretched or flaccid measurements; that produces slightly different global averages (examples: DataPandas’ adjusted global mean 13.12 cm; Let’sTalkSex’s 13.85 cm) [6] [7]. The discrepancies stem from whether measurements were taken by clinical staff, whether self‑reports were adjusted, and how girth was measured (base vs mid‑shaft) [1] [6].
3. Measurement standards matter — and they vary
Key methodological choices change the result: measured erect length from pubic bone to tip (with fat pad compressed) is the accepted standard in the major reviews; flaccid and stretched lengths give different numbers and can’t be directly compared [1] [4]. A systematic review of regional data explicitly warns about lack of standardization across studies and calls this heterogeneity a serious limitation for comparing countries [2].
4. Self‑report bias and statistical corrections
Self‑reported measurements tend to be biased upward; some compilers apply uniform corrections (DataPandas applied a −1.3 cm adjustment to self‑reports and proportional corrections for girth) to try to align surveys with measured data [6]. Not all compilers use the same correction method or justify the size of the correction, which explains part of the variation between publicly circulated “country rankings” [8] [6].
5. Country rankings and ethnicity: smaller differences than popular myths
Many maps and country lists attract attention, but medical reviews and meta‑analyses indicate that differences between populations are smaller than pop culture implies and that studies with large, representative samples are scarce for many countries [1] [2]. The WorldPopulationReview summary and other compendia note that race or region has only marginal effects in higher‑quality data [9].
6. What researchers warn about interpreting the maps
Authors of systematic reviews caution against overinterpreting country rankings because sample sizes, measurement technique, and selection bias vary widely; they explicitly call for standardized measurement protocols in future research [2]. Visual infographics and commercial compilations often combine heterogeneous sources (e.g., Veale et al., Lynn, and public surveys) without harmonized methodology [8].
7. Girth: less publicized but often similar across reviews
Girth (circumference) is consistently reported near 11.6 cm erect in clinician‑measured reviews, and many consumer sites use similar mid‑11 cm figures for circumference even when length estimates drift slightly [1] [5] [7]. Some consumer compilations report girth around 12 cm or slightly lower depending on their data sources and corrections [7] [10].
8. Practical takeaways and limitations for readers
If you need a medically grounded point estimate, the best‑cited measured reviews place average erect length at ~13.1 cm and erect girth at ~11.66 cm [1]. Available sources repeatedly warn that methodological heterogeneity limits fine‑grained country comparisons and that self‑reporting inflates averages unless corrected [2] [6]. For any claim about “the biggest” or “smallest” country, the underlying studies and measurement methods must be examined [8] [2].
Sources used: Veale and related systematic reviews summarized on Wikipedia and science reporting [1] [4], clinical and patient summaries [3] [5], a 2024 WHO‑region meta‑analysis note [2], and contemporary data compilers that illustrate methodological variation and corrections [6] [7] [8].