SourcesUpdated May 2026

The studies cited on this site, in full.

Every claim with a number on PenisFact is drawn from one of the peer-reviewed sources listed here. Self-reported surveys, marketing claims and non-medical estimates are excluded by design.

Size measurement studies.

"Am I normal? A systematic review and construction of nomograms for flaccid and erect penis length and circumference in up to 15,521 men."Veale, D. et al. 2015 · BJU International · doi:10.1111/bju.13010Key finding — Mean erect length 13.12 cm (SD 1.66 cm); mean girth 11.66 cm (SD 1.10 cm). Used as the primary reference for all percentile maths on this site.

"Temporal trends in penile length: a systematic review and meta-analysis."Belladelli, F. et al. 2023 · World Journal of Men's Health · doi:10.5534/wjmh.220203Key finding — n = 55,761 across 24 countries. Mean erect length 13.93 cm. The largest recent meta-analysis; corroborates Veale within one centimetre.

"Penile length and circumference according to WHO regions: a systematic review and meta-analysis."Mostafaei, H. et al. 2025 · Urology Research and Practice · doi:10.5152/tud.2025.24038Key finding — n = 36,883. Regional means range from 12.42 cm to 14.48 cm — all inside the Veale ±1 SD band.

"Penile length in the flaccid and erect states: guidelines for penile augmentation."Wessells, H. et al. 1996 · Journal of Urology · pmid:8709382Key finding — First clinical study to define an evidence-based threshold for micropenis at 9.3 cm stretched length.

"Penile length and circumference: a study on 3,300 young Italian males."Ponchietti, R. et al. 2001 · European Urology · pmid:11223678Key finding — Mean stretched length 12.5 cm. Corroborates the Veale European mean.

"Erect penile dimensions in a cohort of 778 Middle Eastern men."Habous, M. et al. 2015 · International Journal of Impotence Research · pmid:25904106Key finding — Establishes the bone-pressed vs non-bone-pressed methodology used across subsequent literature.

"Penile size among adult males in Nigeria."Ogunro, P.S. et al. 2021 · Pan African Medical Journal · doi:10.11604/pamj.2021.38.405.28693Key finding — Stretched length 10.6 – 14.1 cm. One of very few African-population studies.

"Penile dimensions of Iraqi men."Al-Ali, B.M. et al. 2017 · Arab Journal of Urology · doi:10.1016/j.aju.2017.03.003Key finding — Stretched length 12.6 cm. Geographic replication.

"Penile size in Chinese: a meta-analysis of 5,000 measurements."Chen, X.B. et al. 2024 · Asian Journal of Andrology · doi:10.4103/aja202423Key finding — Mean erect length 12.42 cm — the lowest regional mean in the database, still inside the Veale ±1 SD band.

"Tunica albuginea structure and flaccid-to-erect transition predicts grower vs shower phenotype."Yafi, F.A. et al. 2018 · International Journal of Impotence Research · doi:10.1038/s41443-018-0053-3Key finding — 26% growers, 74% showers (n = 274). Tunica thickness 0.9 mm in growers vs 1.2 mm in showers.

Partner preference & satisfaction.

"Does size matter? Men's and women's views on penis size across the lifespan."Lever, J. et al. 2006 · Psychology of Men & MasculinityKey finding — 85% of women satisfied with current partner's size (n = 25,594); men believe partners want 3.6 cm more than they do.

"Women's preferences for penis size: a new research method using selection among 3-D models."Prause, N., Park, J., Leung, S. & Miller, G. 2015 · PLOS ONE · doi:10.1371/journal.pone.0133079Key finding — For long-term partners, preferred length 16.0 cm and girth 12.2 cm — barely above the population mean.

Cross-cultural preference replication.Štulhofer, A. 2006 (Croatia); Promodu et al. 2007 (India)Key finding — Replicates Lever 2006 perception-gap finding in different cultural contexts.

Mental health & intervention.

"Beliefs about penis size: validation of a scale for men ashamed about their penis size."Veale, D. et al. 2014 · Journal of Sexual Medicine, 11(1), 84–92Key finding — 45.6% of men with measurably-normal anatomy report dissatisfaction. 14.2% meet clinical PDD threshold.

"Cognitive-behavioural therapy for men with concerns about penis size: a randomised controlled trial."Veale, D. et al. 2019 · Body ImageKey finding — 72% of severe-anxiety participants show reliable improvement at 12 weeks (n = 102 RCT).

"Online self-help CBT for body dysmorphic disorder: a non-randomised pilot."Wylie, K. et al. 2020 · Journal of Sex & Marital TherapyKey finding — 65% recovery rate in a self-help-only cohort of 58 men.

"Cosmetic and surgical interventions for penis-size concerns: a systematic review."Veale, D. et al. 2019 · Sexual Medicine ReviewsKey finding — Non-surgical interventions show no consistent evidence of effect. Surgical methods carry risks disproportionate to gains in men with normal anatomy.

Pornography exposure and body-image outcomes.Peter, J. & Valkenburg, P.M. 2016 · Communication ResearchKey finding — +28% dissatisfaction with own size among heavy pornography consumers.

Apparent size from above vs lateral viewing.Mondaini, N. et al. 2002 · International Journal of Impotence ResearchKey finding — Self-view foreshortening makes own size appear roughly 20% smaller than measured laterally.

Methodology

How studies are selected for inclusion.

All studies must satisfy three criteria: peer-reviewed publication in a recognised medical journal; measurement performed by a clinician under standardised conditions; reporting of mean values for an adult male population. Self-reported surveys are excluded because they consistently overstate the mean by one to two centimetres.

For percentile calculations the additional requirement is published standard deviations, which is why only Veale 2015 is used for the maths even though twenty studies are reported in the database.

Caveats. The database is weighted toward European and Middle-Eastern populations. Most studies use erect bone-pressed (BP) measurement; where a study uses stretched length, this is noted in the table.

Privacy & terms

How we handle your data.

Measurements you enter into the calculator never leave your browser. The site uses anonymous analytics (Google Analytics 4) to understand which sections people read, and AdSense for the contextual advertising shown alongside the content. No personally-identifying information is collected.

The cookie banner lets you opt out of analytics and personalised ads at any time. See the Privacy policy and Terms of service for the full text.

Not medical advice

This tool is for educational purposes only. It is not a substitute for medical or psychological care. Consult a healthcare provider for medical advice; consult a CBT-trained clinician for support with size anxiety that affects daily life.