How My Size Report Estimates Your Percentile
The calculator estimates percentiles from a published reference distribution. This page explains the underlying research, which sample sizes apply to erect measurements, and what the estimate can and cannot tell you.
The 2015 reference study
Veale and colleagues reviewed 20 studies involving 15,521 men across measurement categories. The mean erect length was 13.12 cm (5.16 inches), based on 692 measurements, and mean erect circumference was 11.66 cm (4.59 inches), based on 381 measurements. These smaller erect-measurement samples must not be confused with the overall review sample.
The 2025 systematic review
Mostafaei and colleagues included 33 studies and 36,883 participants. The pooled mean erect length was 13.84 cm from 5,669 erect measurements, and mean erect circumference was 11.91 cm from 5,168 erect measurements. The review searched studies published up to February 2024 and included measurements taken by healthcare professionals. DOI: 10.5152/tud.2025.24038.
How the calculator estimates percentiles
The calculator compares length and girth separately with its stated reference distribution. These are modelled estimates, not a direct count of every adult man and not a diagnosis.
Why the 2025 averages are not a replacement model
A mean alone does not provide the full distribution needed to calculate percentiles. We therefore present the 2025 figures as updated context rather than claiming to derive a new percentile model from those averages.
Limitations
Studies can differ in participant selection, measurement technique and sample size. Results may also vary with measurement consistency. Treat the estimates as informational, not medical advice.
My Size Report provides a private, calculator-led way to understand measurements against published research. Results are informational and should not be treated as medical advice.