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What large-scale studies exist measuring erect penis length by age group?
Executive summary
Large, systematic efforts exist that pool many individual studies to report erect penile length; the largest meta-analyses cover tens of thousands of men and report mean erect lengths near 13–14 cm (about 5.1–5.5 in) and show differences by region and over time (pooled erect mean 13.93 cm, 95% CI 13.20–14.65) [1] [2]. Available systematic reviews/meta-analyses include one that pooled 36,883 men with 5,669 measured erect lengths (mean 13.84 cm) [2] and another that assembled data from studies with erect measurements on 18,481 men within a larger dataset of >40,000 participants [3] [4].
1. What "large-scale" studies exist — the meta-analyses and their scale
Two recent, large systematic reviews and meta-analyses are the clearest examples of large-scale measurement: a 2024 systematic review that included 33 studies with 36,883 participants and reported an erect mean based on 5,669 measured men of 13.84 cm (standard error reported) [2], and a World Journal of Men’s Health systematic review/meta-analysis that pooled data from studies spanning 1942–2021 and reported pooled erect-length data from 18,481 men within a total sample of tens of thousands (flaccid/stretched/erect denominators: 40,251; 44,300; 18,481) [3] [4]. The WJMH pooled estimate for erect length was 13.93 cm (95% CI 13.20–14.65) and the authors analyze temporal trends and geographic differences [1].
2. What age coverage and age‑group reporting looks like in those studies
The large meta-analyses primarily aggregated adult studies and generally included men aged 17–86 in the pooled data; the WJMH review explicitly states included studies had participants aged ≥17 and reported an age range of 18 to 86 across studies [3] [4]. The systematic reviews adjust for subject age when modeling trends, but most primary studies report adult averages rather than finely stratified, population‑representative age bands [1] [2]. Available sources do not provide a single, standardized large study that publishes erect‑length nomograms by narrow age groups across the full adult lifespan.
3. Do these large studies provide age‑group breakdowns (e.g., 18–24, 25–34)?
The pooled meta-analyses report overall means and examine age as a covariate in meta‑regressions, but they do not all present consistent, detailed erect‑length tables by narrow age bands in the pooled results [1] [2]. Some primary studies included in the reviews may have reported age‑stratified results, but the systematic reviews focus on pooled means and regional/time trends rather than producing a single, high‑resolution age‑by‑age chart for erect length [2] [4]. Therefore, a single consolidated, large‑sample dataset publicly reporting erect penis length across many fine age bins is not clearly identified in the cited reviews (not found in current reporting).
4. Geographic and temporal patterns — why numbers vary
Both reviews emphasize geographic variation and time trends. The WJMH meta‑analysis finds erect length varies by region and increased significantly over recent decades (authors report a 24% increase over 29 years after adjusting for region and age) [1]. The 2024 WHO‑region meta‑analysis pooled many studies and likewise documents regional differences in stretched, erect, and flaccid measures [2]. Differences arise from measurement methods (investigator‑measured vs. self‑reported), how the penis was measured (pushing fat pad to bone, injected vs. spontaneous erection), and the composition of study populations (clinical vs. community samples) [1] [2].
5. Measurement method matters — sources of potential bias
Both systematic reviews stress that who measures and how they measure affect results. Studies measured by health professionals yield different averages than self‑reported datasets; injected or pharmacologically induced erections can differ from spontaneous ones; and some studies adjusted for pubic fat by pressing to the pubic bone while others did not [2] [1]. These methodological differences create heterogeneity that complicates direct age‑group comparisons across studies [1].
6. Practical takeaways and where the gaps remain
If you want large-sample benchmarks for adult erect length, consult the pooled estimates: ~13.8–13.9 cm (roughly 5.1–5.5 in) from major meta-analyses [2] [1]. If you need erect‑length by fine age strata, available large meta-analyses do not present a single standardized age‑band nomogram; individual primary studies may contain age subgroups but are heterogeneous and often small compared with the pooled totals (not found in current reporting; [2]; p1_s7). For research requiring age‑by‑age norms, the remaining work is to assemble primary datasets with harmonized measurement protocols or to request age‑stratified data from study authors included in the meta‑analyses.
If you want, I can (a) extract which primary studies in these reviews reported any age subgroups, or (b) summarize methodological differences across the largest contributing studies to help decide which dataset best matches your needs.