Average Erect Penis Length
The average length of an erect penis is between 5.1 and 5.5 inches (12.95-13.97 cm), with measurements likely toward the lower end of this range after accounting for volunteer bias. Most men incorrectly believe the average erect penis length exceeds 6 inches (15.24 cm), but this misconception stems from studies with self-reported measurements that suffered from volunteer and social desirability biases. 1
Evidence-Based Measurements
Most Recent and Comprehensive Data
- A 2021 review analyzing 10 studies where researchers directly measured erect penises (n=1,629) found a combined mean length of 5.36 inches (13.61 cm) 1
- For stretched penis measurements (considered a reliable proxy for erect length), the mean from 21 studies (n=13,719) was approximately 5.11 inches (12.98 cm) 1
Regional Variations
- In a large Vietnamese study (n=14,597), the median stretched penile length was 14.67 cm (5.78 inches) 2
- A Middle Eastern study (n=778) found a mean erect length of 14.34 cm (5.65 inches) when measured from the pubic bone to the tip 3
- In the United States, a study of 1,661 men found a mean erect penile length of 14.15 cm (5.57 inches) 4
Important Considerations
Measurement Methods
Different measurement techniques yield different results:
- Bone-to-tip (pubic bone to penile tip) measurements are generally longer than skin-to-tip measurements
- The Middle Eastern study found a difference of approximately 1.8 cm between these two measurement methods 3
- Method of achieving erection can influence dimensions 4
Factors Affecting Size
- Body Mass Index (BMI): Higher BMI correlates with shorter apparent length (r = -0.283) due to the fat pad at the base of the penis 3
- Age: Weak negative correlation between age and erect penile length (r = -0.177) 3
- Erectile function: Men with erectile dysfunction tend to have shorter penises (11.2 cm) compared to men without ED (12.9 cm) 5
Clinical Implications
Psychological Impact
- Most men incorrectly believe the average erect penis is larger than it actually is
- A majority of men wish they were larger, with some seeking surgical interventions 1
- Counseling with accurate information about penis size can help alleviate concerns for men worried about having a small penis 1
Surgical Considerations
- Penile lengthening surgeries are considered risky by the American Urological Association
- Most men seeking such surgery actually have normal-sized penises 1
Conclusion
The scientific evidence consistently shows that the average erect penis length is between 5.1 and 5.5 inches (12.95-13.97 cm), which is significantly smaller than the commonly believed 6+ inches. Understanding these accurate measurements is important for both clinical practice and patient education to address concerns about penile size.