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.
Why This Meta-Analysis?
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✓ Medical Measurements Only:
All measurements taken by medical professionals, not self-reported
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✓ Explicit Measurement Protocols:
Included studies used clinician measurements; protocol differences still exist and are a real limitation
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✓ Honest Sample Sizes:
We now show the specific n for each measure instead of applying the 15,521 headline to erect length or girth
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✓ Global Representation:
Data from Europe, Asia, Africa, and Middle East
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✓ 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
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Self-reported measurements - Proven to overestimate by 0.5-1.5 inches
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Internet surveys - Selection bias toward larger sizes
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Condom company data - Customers not representative of population
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Studies before 1990 - Inconsistent measurement protocols
-
Stretched flaccid only - Less accurate than erect measurements
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Studies with n < 50 - Sample size too small for reliability
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Porn industry statistics - Extreme selection bias
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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:
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:
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Geographic bias:
More data from certain regions (Middle East, Europe) than others (Africa, South America)
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Age range:
Most studies focus on adults 18-60; limited data on older populations
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Volunteer bias:
Men who volunteer for studies might differ from general population
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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:
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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.
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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.
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King, B. M. (2020).
"Average-Size Erect Penis: Fiction, Fact, and the Need for Counseling."
Journal of Sex & Marital Therapy, 47(1), 80-89.