Is Average Penis Size Increasing? What the Study Shows

Researchers from Stanford and Milan pooled 75 studies with 55,761 men, published between 1942 and 2021 (Belladelli et al., World Journal of Men's Health, 2023). Only measurements taken by researchers were included, not self-reports.

After adjusting for region, age and the type of population, erect length increased by about 24% over 29 years. In the authors' model, that's from 12.3 cm to 15.2 cm. Across all studies, the pooled averages were 8.7 cm flaccid, 12.9 cm stretched and 13.9 cm erect.

Only one measurement moved. If penises were really growing, you'd expect flaccid and stretched length to grow too. They didn't. Erect length is also the hardest one to measure the same way twice: some studies used an injection to cause an erection, others relied on a spontaneous one, which is often less complete.

The studies are very different. They come from different countries, decades and groups of men, from young conscripts to urology patients. The statistical heterogeneity was extreme (I² = 98.9%), which means the studies disagree far more than chance would explain.

It compares studies, not men. The analysis looks at when each study was published, not at the same population measured again over time. A shift in who gets measured, and how, can look like a shift in size.

The authors suggest that earlier puberty or environmental exposures could play a role, but the study can't show a cause, and they call for more research to confirm the trend.

The best single reference is still Veale et al. (2015): 15,521 men, measured by health professionals with a standard protocol. Average erect length was 13.12 cm (5.17 in) and girth 11.66 cm (4.59 in). The 2023 pooled value of 13.9 cm is a little higher, mostly because it includes a wider range of studies and methods.

The 15.2 cm figure from the headlines is a model estimate for studies published around 2021. It isn't a new measured average, and it shouldn't be used as a benchmark. Our calculator keeps the Veale baseline because it's the largest dataset with a consistent method.

How our data works →

Not much. Even if the trend is real, it describes averages across studies, not your own body. If you want to know where you stand, measure properly, bone-pressed and erect, and compare yourself with a clinical baseline, not with a headline.

How to measure correctly →

Why it looks smaller than it really is →

Enter your measurements and compare them with 15,521 clinically measured men.

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• Belladelli F, Del Giudice F, Glover F, et al. Worldwide temporal trends in penile length: a systematic review and meta-analysis. World J Mens Health. 2023;41(4):848–860. doi:10.5534/wjmh.220203
• Veale D, Miles S, Bramley S, Muir G, Hodsoll J. Am I normal? A systematic review and construction of nomograms for flaccid and erect penis length and circumference in up to 15 521 men. BJU Int. 2015;115(6):978–986.