What do medical studies say about average penis and shoe sizes?
Executive summary
Medical research consistently finds no reliable link between men’s shoe size and penile length; a prospective study of 104 men found median stretched penile length 13 cm (≈5.1 in) and median UK shoe size 9 but concluded “the supposed association … has no scientific basis” [1]. Large pooled analyses and summaries put average erect penis length near 5.1 inches (≈13 cm) and average flaccid length lower, while multiple commentaries and reviews repeat that foot size is an unreliable predictor [2] [3].
1. The core finding: shoe size does not predict penis length
Clinical measurement studies designed to test the folk belief “big feet = big penis” report either no correlation or only weak, inconsistent associations; a prospective UCL study measuring stretched penile length in 104 men reported a median length of 13 cm and median UK shoe size 9 but concluded there was no scientific basis for the association [1]. Reviews and media summaries repeat that conclusion: popular outlets cite the same clinical work and broader reviews to state the myth is not supported by evidence [4] [5].
2. What the medical numbers say about average penile length
Large-data syntheses and widely cited reviews place average erect length at about 5.16 inches (~13.1 cm) and average flaccid length lower (for example, a 2014 pooled analysis quoted in Business Insider reports average flaccid length 3.61 in and erect length 5.16 in) [2]. The 104‑person UCL sample found an average (median) stretched/flaccid‑stretched length of about 13 cm (≈5.1 in), which aligns with other clinical series referenced in the literature [1] [3].
3. Study design matters — how penis size was measured
Reliable estimates come from clinician‑measured data, not self‑reports. The UCL study used “stretched penile length” measured by urologists, a common clinical proxy for erect length that many papers accept for consistency [1] [3]. Larger pooled studies that informed the commonly cited averages used standardized procedures and excluded samples with congenital anomalies or prior surgery to avoid bias [3]. Media pieces tend to draw on those clinically measured series when discussing averages [2].
4. Conflicting or nuanced findings in the literature
Some older or smaller studies show weak correlations between penile length and somatometric measures (height, foot length) in limited samples, but reviews and larger analyses conclude these are unreliable or not generalizable [3] [6]. ResearchGate notes occasional positive correlations in subsets but emphasizes most proposed cues (height, weight, shoe size, finger ratios) are unreliable predictors [3]. Thus the dominant interpretation across sources is skepticism toward a meaningful predictive relationship.
5. Why the myth persists — cultural and psychological drivers
Popular culture and anecdote keep the shoe‑size heuristic alive despite clinical evidence to the contrary; lifestyle and entertainment sites repackage the original studies into catchy headlines, and conversion charts and forums perpetuate simple mappings between shoe and penis sizes even when science does not support them [7] [5]. Commentaries also note social anxieties and body‑image pressures that lead people to latch on to quick physical cues despite poor predictive value [8].
6. Limitations and gaps in reporting
Available sources do not mention certain details readers might expect: comprehensive, population‑representative studies linking measured penis length and measured foot length across very large, diverse cohorts are limited in the provided materials (not found in current reporting). Some smaller studies and older datasets exist (e.g., samples of 63 or several hundred), but pooled meta‑analytic coverage beyond what is cited in the 2014 pooled work and the UCL prospective study is only summarized rather than exhaustively listed in the provided sources [6] [3].
7. Bottom line for readers and clinicians
Clinically measured data and peer‑reviewed summaries consistently show average erect penis length around 5.1 in (≈13 cm) and do not support using shoe size as a predictive tool [1] [2] [3]. If someone seeks reliable information about penile norms or has concerns about size, the evidence in the cited clinical literature supports consulting healthcare professionals rather than relying on heuristics like shoe size [1] [3].
Sources cited: primary clinical study and reviews summarized above [1] [3] [2], media and commentary that interpret those studies [5] [4], and supplementary literature noting limited correlations and psychosocial context [8] [6] [7].