Research
Men and Penis Size
What the evidence says, rather than what the internet says.
The reference study
The numbers most clinics get wrong.
The most clinically useful data comes from Veale et al. (2015), a systematic review that pooled measurements taken by health professionals using standard procedures, and excluded men with penile abnormalities, prior surgery or complaints about size.
11.66 cm / 4.59 in
Mean erect circumference. Standard deviation 1.10 cm.
9.31 cm / 3.66 in
Mean flaccid circumference.
Roughly 89% of men measure below 13 cm / 5.1 in erect girth, and about 98% below 14 cm / 5.5 in. One honest caveat: the erect-girth figure rests on a smaller subset (n = 381) than the flaccid figure (n = 9,407), so erect percentiles are useful rather than precise.
The girth estimator uses this study, so it shows where a projected result would sit against the distribution rather than just quoting a centimetre gain.
Perspective
Most men asking are already average.
That is the consistent finding across the literature: the large majority of men who seek augmentation measure within the normal range. Concern about size correlates far more strongly with how a man feels about his body than with his actual measurements.
- Comparison is distorted. Pornography is selected for outliers, and self-comparison from above foreshortens your own view.
- Partner surveys consistently rank girth above length where either matters, and rank both below other factors entirely.
- A small number of men have body dysmorphic disorder, where no physical result resolves the distress. Surgery and filler both perform badly in that group, which is why we screen for it.
If a physician never raises any of this with you, be cautious. Wanting a change is legitimate; being sold one is different.
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About this page
Last reviewed on 30 July 2026.
Medically reviewed by Dr Gary Horn — founder of Androfill, consultant plastic and reconstructive surgeon and uro-andrologist, GMC 4267803.
General information only, not a substitute for a consultation. Individual results vary from person to person.