Methodology

Veale D, et al. 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.

This systematic review pooled clinically measured data from up to 15,521 men across multiple studies, measured by health professionals with a standardized bone-pressed technique rather than self-reported. That sample size is what makes the resulting nomograms the reference baseline for global comparisons.

Erect length

13.12 cm ± 1.66 SD

Erect girth

11.66 cm ± 1.10 SD

Flaccid length

9.16 cm ± 1.57 SD

Flaccid girth

9.31 cm ± 0.90 SD

The world map and country baselines cover 134 countries and are compiled from public aggregators (e.g. WorldData.info).

Reliability caveat: these figures mix self-reported surveys, small samples and inconsistent measurement protocols. They are not peer-reviewed and vary widely in quality. Treat every country-level number as an indicative estimate, not a clinical reference.

The country compilations publish means only. To place a country average on a distribution, the app falls back to the erect standard deviations from the Veale review: 1.66 cm for length and 1.10 cm for girth.

Where a country ever ships its own SD (the dataset supports optional per-country SD fields), that value is used instead. Flaccid comparisons always use the global baseline, because country data exists for erect measurements only.

Values are classified into six standard-deviation bands around the active baseline mean. The population shares are exact normal-distribution band probabilities:

• SmallBottom 2%below −2 SD2.28% · ≈ 23 are smaller
• Below averageBottom 16%−2 to −1 SD13.59% · ≈ 136 are smaller
• AverageMiddle 68%−1 to +1 SD68.27% · ≈ 683 land here
• BigTop 16%+1 to +2 SD13.59% · ≈ 136 are larger
• LargeTop 2%+2 to +3 SD2.14% · Only ≈ 21 are larger
• HugeTop 0.1%above +3 SD0.13% · Only ≈ 1 is larger

A percentile is the cumulative distribution function of the baseline normal distribution evaluated at your value, the share of the population below it. The CDF uses the Abramowitz–Stegun 7.1.26 error function approximation (maximum error ≈ 1.5×10⁻⁷).

Displayed percentiles follow one rounding rule everywhere: whole numbers between the 5th and 95th percentile, one decimal outside that band with a "1 in N" intuition, and the extremes cap at 0.1% / 99.9% ("fewer than 1 in 1,000"), so the app never claims a literal 0% or 100%.

The baseline, every verified national study and the research behind our guides are listed on the sources page.

How data is sourced, calculated and corrected — and how funding is kept separate from statistics — lives in the editorial policy.