What large-scale, peer-reviewed studies have measured male genital size across different racial or ethnic groups?
Executive summary
Large, peer‑reviewed efforts exist but they cluster into two types: systematic reviews/meta‑analyses that pool clinician‑measured studies across countries and many smaller, regional clinician‑measured or self‑report studies that attempt racial/ethnic comparisons. For example, a 2025 systematic review/meta‑analysis pooled 33 studies with 36,883 participants across WHO regions (reporting by geography, not always by race/ethnicity) [1]; earlier large syntheses and nomograms have aggregated up to ~15,521 men in clinician‑measured datasets [2] [3].
1. What counts as “large‑scale, peer‑reviewed” research on this question?
The most defensible large‑scale work is systematic reviews and meta‑analyses that assemble clinician‑measured studies rather than relying on self‑reports. A recent systematic review titled “Who has the Biggest One?” (Mostafaei et al.) searched PubMed, Embase, Scopus and Cochrane and included 33 studies totaling 36,883 men, reporting penis length and circumference by WHO geographic regions; that paper is peer reviewed and published in Urology Research and Practice in 2025 [1] [4]. Earlier influential syntheses and nomograms also combined clinician‑measured data across thousands of men (up to ~15,521 in some aggregated reviews) and were used to set normative ranges [2] [3].
2. Do those large reviews report results by race or ethnicity?
The systematic reviews tend to present results by geography or WHO region rather than by conventional racial/ethnic categories. Mostafaei et al.’s meta‑analysis explicitly organized findings according to WHO regions (geography) and included studies in which a healthcare professional measured the penis; it did not primarily present global averages stratified by race in the standard census sense [1] [4]. Other meta‑analyses have focused on country or region (for example, a 2024 Andrology meta‑analysis concentrating on Chinese men and placing them into a global context) [5] [6].
3. Large single‑study datasets that attempted ethnic comparisons
There are some large studies and compilations that attempt ethnic breakdowns, but many are older, heterogeneous or rely on self‑report. Reviews cite clinician‑measured datasets sampled in particular countries or cities (for example, multiple Chinese studies were pooled in the 2024 Wang meta‑analysis of Chinese men) [6] [5]. Public summaries and secondary sources note U.S. studies (e.g., a 2014 U.S. sample of ~1,600 men) that compared White, Black, Asian, Native American and Pacific Islander groups and found intergroup differences of less than an inch, but these are often reported in non‑peer venues or mixed clinician/self‑report samples [7].
4. Methodological limits that matter for racial/ethnic comparisons
Experts repeatedly warn the literature is plagued by biases and measurement heterogeneity: many datasets are small, rely on self‑measurement (which inflates values), or sample convenience populations; robust studies have been concentrated in Europe and the Middle East, leaving global representativeness thin [8] [3]. Reviews restrict inclusion to clinician‑measured data to reduce bias, but even then, sampling frames, age ranges, measurement protocol (stretched flaccid vs erect), and how race/ethnicity is defined vary across studies — undermining direct race‑by‑race comparisons [1] [6].
5. What the peer‑reviewed aggregates actually show about race differences
Aggregated, clinician‑measured datasets show geographic/regional variation but heavy overlap among groups: meta‑analytic work emphasizes regional averages and broad overlap rather than clean, predictive racial differences [1] [3]. Some authors and historical datasets (e.g., Rushton and follow‑ups) have claimed systematic race differences across many populations — claims that remain controversial and are criticized for methodology and ideological bias in secondary literature [9] [10]. Contemporary systematic reviewers prioritize measurement rigor and caution that distributions within groups are much larger than between‑group mean differences [1] [2].
6. Bottom line for readers asking “Which large studies did this?”
Look first to systematic reviews/meta‑analyses that pool clinician‑measured studies: the 2025 Urology Research and Practice meta‑analysis that included 33 studies and 36,883 men is the clearest recent large‑scale peer‑reviewed synthesis [1] [4]. Other major aggregations and nomograms (cited in review literature) combine clinician‑measured datasets up to ~15,521 men and country‑level meta‑analyses (e.g., the 2024 Andrology paper on Chinese men) [2] [3]. For explicit race/ethnicity comparisons, source papers are more fragmented: some U.S. samples and regional studies report ethnic breakdowns, but these are smaller and heterogeneous, and their conclusions are limited by measurement and sampling issues [7] [6].
Limitations and where to read next: seek the Mostafaei et al. 2025 systematic review/meta‑analysis for the largest pooled, peer‑reviewed dataset organized by region [1]; consult the 2024 Andrology meta‑analysis for intensive national/regional work [5]. Available sources do not provide a single, universally accepted large clinician‑measured study that cleanly and reliably compares standardized racial/ethnic groups across the globe without the methodological caveats above (not found in current reporting).