Methodology & data

We'd rather show our work than make you trust a black box. Here's everything the calculator uses.

Primary dataset

Veale D, Miles S, Bramley S, Muir G, Hodsoll J. (2015). 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 International. Clinician-measured, bone-pressed, pooled from 17 studies.

Metric	Mean	SD	n
Erect length	13.12 cm	1.66	692
Erect girth	11.66 cm	1.10	381
Stretched length	13.24 cm	1.89	14,160
Flaccid length	9.16 cm	1.57	10,704
Flaccid girth	9.31 cm	0.90	9,407

How percentiles are computed

For each metric we model the population as a normal (bell-curve) distribution using the mean and standard deviation above. Your percentile is the cumulative probability below your measurement: Φ((x − mean) / SD).

Volume models the shaft as a cylinder, V = (girth² ÷ 4π) × length; its percentile is a delta-method estimate.

Bone-pressed correction

The reference data is bone-pressed. If you measure non-bone-pressed, we add 1.0 cm to your length before comparing. Girth needs no correction.

Country comparison

Lower-quality data — read this

Country averages come from a worlddata.info aggregation of heterogeneous studies, many self-reported and none nationally representative. We only have per-country means, so the "percentile within a country" reuses the clinical standard deviation as an approximation.

Women's-preference reference

Where preference figures appear, they come from Prause et al. (2015), PLoS ONE, which used 3D-printed models rather than self-report.

Limitations

Real distributions aren't perfectly normal, especially at the extremes.
Erect-dimension sample sizes in Veale 2015 are smaller than stretched/flaccid.
This tool is educational and is not a medical assessment.