How we turn medical data into accurate percentiles
692
Erect Length Sample (Veale)
381
Erect Girth Sample (Veale)
15,521
Largest Veale Measure Category
36,883
Men in 2025 Clinical Review
Our Primary Data Source
Our percentile calculator uses Veale et al. (2015) because that paper published pooled means and standard deviations suitable for nomograms. A larger 2025 clinician-measured meta-analysis is now shown as modern context rather than being forced into a percentile model it did not publish in the same form.
Veale et al. (2015) Meta-Analysis
Published in BJU International, this systematic review and meta-analysis combined data from
20 clinician-measured study samples. It remains especially useful for percentile modeling because it published pooled standard deviations and constructed nomograms, but its erect subsets were much smaller than the headline 15,521 figure.
692
Erect Length n
381
Erect Girth n
5.16"
Mean Length
4.59"
Mean Girth
2025 Update: Mostafaei et al.
A newer systematic review and meta-analysis included 33 studies and 36,883 men overall, with 5,669 erect-length measurements and 5,168 erect-circumference measurements. It reported pooled means of 13.84 cm erect length and 11.91 cm erect circumference. We display those means as a modern cross-check, but we do not manufacture a new percentile curve from the paper's standard errors.
✓ Medical Measurements Only:
All measurements taken by medical professionals, not self-reported
✓ Explicit Measurement Protocols:
Included studies used clinician measurements; protocol differences still exist and are a real limitation
✓ Honest Sample Sizes:
We now show the specific n for each measure instead of applying the 15,521 headline to erect length or girth
✓ Global Representation:
Data from Europe, Asia, Africa, and Middle East
✓ Peer Reviewed:
Published in respected medical journal with rigorous review process
Studies Included in Our Dataset
These are the primary studies that contributed to our calculator's database:
Study
Year
Sample Size
Country
Population
Wessells et al.
1996
80
USA
Adult men
Schneider et al.
2001
111
Germany
Young adults (18-19)
Promodu et al.
2007
301
India
Adult men
Herbenick et al.
2014
1,661
USA
Sexually active men
Acuña et al.
2010
800
Colombia
Military recruits
Khan et al.
2012
609
Pakistan
Adult patients
Habous et al.
2015
778
Saudi Arabia
Adult men
Aslan et al.
2011
2,276
Turkey
Military personnel
Chrouser et al.
2013
5,122
Tanzania
Adult men
Söylemez et al.
2012
1,132
Turkey
Healthy volunteers
Note: This represents a selection of the most significant studies. The complete meta-analysis includes
additional smaller studies that meet our inclusion criteria.
How Medical Measurements Are Taken
Consistency in measurement is crucial. All studies in our dataset follow these standardized protocols:
📏
Length Measurement
Measured from pubic bone to tip (bone-pressed), using rigid ruler,
with penis perpendicular to body. Room temperature controlled.
⭕
Girth Measurement
Circumference at midshaft or widest point, using measuring tape.
Consistent location across subjects within each study.
🏥
Professional Measurement
All measurements by medical professionals or trained researchers.
No self-reported data included in our calculations.
🌡️
Standardized Conditions
Controlled room temperature, privacy ensured, consistent time of day
when possible, same position for all subjects.
💊
Erection Method
Pharmacologically-induced (injection) or self-stimulated in private.
Maximum erection verified before measurement.
📊
Multiple Measurements
Many studies take 3 measurements and use the average,
reducing measurement error and increasing accuracy.
What We Don't Include
Studies We Exclude and Why
Self-reported measurements - Proven to overestimate by 0.5-1.5 inches
Internet surveys - Selection bias toward larger sizes
Condom company data - Customers not representative of population
Studies before 1990 - Inconsistent measurement protocols
Stretched flaccid only - Less accurate than erect measurements
Studies with n < 50 - Sample size too small for reliability
Porn industry statistics - Extreme selection bias
Dating app surveys - Self-selection and exaggeration
Why Self-Reported Data Is Problematic
Studies consistently show that self-reported measurements average 0.5-1.5 inches larger than
medical measurements. This is due to:
• Measuring from the side instead of top
• Not pressing firmly against pubic bone
• Measuring at favorable angles
• Rounding up measurements
• Intentional exaggeration
• Selection bias (smaller men don't participate)
How We Calculate Your Percentile
We use statistical modeling based on the normal distribution observed in the data:
The Statistical Method
Penis size follows a normal (Gaussian) distribution. Using the mean and standard deviation
from our dataset, we calculate your exact percentile position.
Z-score = (Your Size - Mean) / Standard Deviation
Percentile = Normal CDF(Z-score) × 100
Our Statistical Parameters
Length
Mean: 13.12 cm (5.16 in)
SD: 1.66 cm (0.65 in)
Girth
Mean: 11.66 cm (4.59 in)
SD: 1.10 cm (0.43 in)
This means 95% of men fall between 4.0-6.3 inches in length and 3.7-5.4 inches in girth.
If you're in this range, you're completely normal.
Our Commitment to Transparency
What We Promise
All our data comes from peer-reviewed medical studies
We never adjust numbers to make people feel better (or worse)
We update our dataset when new quality studies are published
We clearly cite all our sources
We explain our limitations and potential biases
We never save or track your personal measurements
Limitations to Consider
While our data is the best available, it has limitations:
Geographic bias:
More data from certain regions (Middle East, Europe) than others (Africa, South America)
Age range:
Most studies focus on adults 18-60; limited data on older populations
Volunteer bias:
Men who volunteer for studies might differ from general population
Measurement variation:
Slight differences in technique between studies despite standardization
Why We Don't Separate by Race/Ethnicity
The scientific evidence shows minimal statistically significant differences between ethnic groups
when studies use proper methodology. The variations within groups are much larger than between groups.
We use global data to avoid perpetuating stereotypes not supported by medical evidence.
Primary References
Our main sources for those who want to verify:
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, 115(6), 978-986.
Herbenick, D., Reece, M., Schick, V., & Sanders, S. A. (2014).
"Erect penile length and circumference dimensions of 1,661 sexually active men
in the United States." The Journal of Sexual Medicine, 11(1), 93-101.
King, B. M. (2020).
"Average-Size Erect Penis: Fiction, Fact, and the Need for Counseling." Journal of Sex & Marital Therapy, 47(1), 80-89.
Ready to See Your Real Percentile?
Now you know exactly where our data comes from. No tricks, no agenda, just medical science.