What are the published percentile tables (including standard deviations) for erect penis girth from professionally measured studies?

1. What the major reviews actually report

The most-cited systematic review that constructed nomograms (“Am I normal?” by Veale et al.) pooled measured data from clinical studies and simulated 20,000 observations from the weighted mean and pooled standard deviation to generate percentile charts for length and girth, explicitly including erect circumference (girth) in its nomograms ^{[1] [4]}. Other large syntheses and meta-analyses report very similar central values: a later systematic review/meta-analysis that accepted only professionally measured values reported an erect circumference (mean) of about 11.91 cm (standard error 0.18 cm) across included studies ^[5], and encyclopedic summaries commonly cite an erect-girth mean of ~11.66 cm coming from the Veale review ^{[2] [6]}.

2. What primary professionally measured studies add (mean ± SD examples)

Individual professionally measured studies that report erect-girth means and standard deviations are few but informative: a large Italian cohort reported an erect penis circumference mean of 12.03 cm with a standard deviation of 3.82 cm (measured/recorded per protocol) ^[7]. A Chinese meta-analysis reported detailed means and SDs for flaccid measures and constructed its own percentile charts for that population, but erect-circumference SD information was more limited in that regional paper ^[8]. These study-level mean±SD values are what the nomogram-building papers used to simulate percentiles ^{[1] [4]}.

3. Where the percentile tables are and why they vary

Veale et al. produced the explicit percentile nomograms by simulating from a weighted mean and pooled SD, and publication of those nomograms is the primary source of percentiles derived from professionally measured data ^{[1] [4]}. However, later large meta-analyses note substantial heterogeneity across regions and decades and emphasize that erect measurements were relatively scarce: only a handful of studies measured erect circumference directly ^[3]. That scarcity makes percentile estimates sensitive to which studies are included and to between-study variability, so different syntheses can produce different percentile cutoffs even when mean values are similar ^{[5] [9]}.

4. Standard deviations: reported, pooled, and missing

Some papers publish study-specific SDs (for example the Italian study’s erect girth SD = 3.82 cm) while meta-analyses often report standard errors of the weighted mean (e.g., SE 0.18 cm for an 11.91 cm pooled mean) rather than a single pooled SD for erect girth in the text snippets available here ^{[7] [5]}. Veale et al. explicitly calculated a pooled SD and used it to simulate percentiles, but the pooled-SD number and the full percentile table are contained in the original paper’s tables/nomograms rather than uniformly repeated in downstream summaries ^{[1] [4]}. Importantly, some reviews warn that the nomograms do not reflect the differing sample sizes or uncertainty for each measurement type (erect circumference had far fewer observations than flaccid measures) ^[3].

5. Practical takeaways and limitations

Clinically measured erect-girth means from reputable syntheses cluster around 11.6–12.0 cm; individual-study SDs vary (example: 3.82 cm in one large Italian sample), and full percentile tables were produced by Veale et al. by simulation from weighted means and pooled SDs but are imprecise because only a small number of studies contributed erect-girth data ^{[2] [7] [1] [3]}. Readers seeking row-by-row percentiles with the pooled SD used should consult the Veale 2015 nomograms and the tables in the systematic reviews/meta-analyses cited, because summaries and news coverage often report means but omit the pooled-SD and full percentile listings ^{[1] [5] [2]}.