Adult measurements · Statistical reference
Average adult erect penis length is about 5.2–5.5 inches (13–14 cm) in large clinician-measured reviews. The widely cited 2015 review reported 13.12 cm (5.17 inches) in length and 11.66 cm (4.59 inches) in girth. A larger 2023 review reported erect length of 13.93 cm (5.48 inches). These are pooled study averages, not a required size or a diagnosis. Sources and evidence limits.
Penis size has three separate measurements: length, girth and measurement state. Girth means circumference—the distance around the shaft. Erect, flaccid and stretched measurements cannot be compared interchangeably. This guide concerns adult measurements; children and adolescents need age-appropriate assessment.
What are the average erect, flaccid and stretched penis measurements?
The 2015 review reported the following averages. Its total included up to 15,521 men, but each measurement used a different sample; only 692 contributed erect length and 381 erect girth. The full sample was not measured erect.
| Measurement | Mean in cm | Mean in inches | Measurement sample |
|---|---|---|---|
| Erect length | 13.12 | 5.17 | 692 |
| Erect girth (circumference) | 11.66 | 4.59 | 381 |
| Flaccid length | 9.16 | 3.61 | 10,704 |
| Flaccid girth | 9.31 | 3.67 | 9,407 |
| Stretched flaccid length | 13.24 | 5.21 | 14,160 |
Source: Veale and colleagues, BJU International, 2015. Stretched length is measured while the non-erect penis is gently extended. It is a distinct measurement, not an erection.
Why do newer studies report a different average penis length?
Average penis length differs between reviews because they include different studies, populations and measurement procedures. Belladelli and colleagues’ 2023 meta-analysis included 75 studies with 55,761 men across all measurement categories. It estimated mean erect length at 13.93 cm, with a 95% confidence interval of 13.20–14.65 cm. That interval describes uncertainty about the pooled mean, not the range of individual penis sizes. Read the 2023 systematic review.
A newer pooled estimate does not mean every adult’s penis has grown. The 2023 authors reported a temporal trend across studies; this is not evidence that an individual adult will grow by the same percentage. Neither review is a census of every country. Population selection and protocol differences limit comparisons.
What is the difference between average penis size and a typical range?
An average is one summary value; a typical range describes variation around it. The following intervals are calculated statistical estimates, using the 2015 means and standard deviations with a normal-distribution assumption. They are not observed minimums and maximums, medical thresholds or guarantees of function.
| Erect measurement | Calculated interval in cm | Calculated interval in inches |
|---|---|---|
| Length (SD 1.66 cm) | 9.87–16.37 | 3.89–6.44 |
| Girth (SD 1.10 cm) | 9.50–13.82 | 3.74–5.44 |
What do penis-size percentiles mean?
A percentile estimates where a measurement sits within a reference distribution. These percentiles are calculated from the 2015 normal model using length = 13.12 + z × 1.66 and girth = 11.66 + z × 1.10, in centimetres. They are approximations, not counts from a worldwide census.
| Percentile | Erect length | Erect girth |
|---|---|---|
| 5th | 10.39 cm (4.09 in) | 9.85 cm (3.88 in) |
| 25th | 12.00 cm (4.72 in) | 10.92 cm (4.30 in) |
| 50th | 13.12 cm (5.17 in) | 11.66 cm (4.59 in) |
| 75th | 14.24 cm (5.61 in) | 12.40 cm (4.88 in) |
| 95th | 15.85 cm (6.24 in) | 13.47 cm (5.30 in) |
A measurement below the average, or outside this modelled interval, does not by itself establish a disorder. A percentile also describes statistical position rather than health, fertility or sexual ability. The penis size calculator uses the 2015 reference model for educational length and girth comparisons; it does not diagnose a condition.
How should you measure penis length and girth before comparing?
Measure length and girth separately, using a consistent state and technique. For a bone-pressed erect length measurement, place a ruler along the upper side of the fully erect penis and measure from the pubic bone to the glans tip. Exclude any foreskin extending past the glans. For girth, wrap a flexible tape around the mid-shaft without tightening it into the skin.
Bone-pressed and skin-to-tip lengths use different starting points. Mixing them can create a misleading comparison, especially when a fat pad covers the base. Research protocols also differ, so the pooled average should not be described as if every study used an identical bone-pressed method. See the guide to measuring penis length and girth for the method and common errors.
Does flaccid penis size predict erect size?
Flaccid appearance cannot reliably tell you an individual’s erect dimensions. Temperature, tension and arousal affect the non-erect state. A comparison made in a cold room is not equivalent to an erect measurement. Compare the same measurement state and avoid repeatedly checking small day-to-day differences.
Is there a reliable average penis size by country, race or age?
The reviews do not establish a precise average for every country or a rule for predicting an individual’s size from race. Regional pooled results reflect the studies available, their participants and their methods. A country ranking that mixes self-reports with clinician measurements is not a consistent comparison.
Adult reference values also should not be used to judge development during puberty. Read how penis size changes during puberty for developmental context and how penis size can change with age for adult concerns. Those are separate questions from the average adult measurement.
Why are self-reported penis measurements less comparable?
Self-reported measurements can differ in technique, erection state and reporting accuracy. The reviews cited here selected investigator or health-professional measurements. Independent measurement reduces one source of bias but does not remove differences between studies. Learn how social desirability bias affects self-reported penis size.
Does being below average mean you have a micropenis?
No. Micropenis is a clinical diagnosis based on correctly measured stretched penile length more than 2.5 standard deviations below the appropriate reference mean. A home erect measurement or calculator percentile is not the diagnostic test. The clinical review of micropenis also distinguishes a genuinely short penis from one concealed by surrounding tissue.
When should concerns about penis size be assessed?
Seek a qualified clinician’s assessment for new shortening, pain, new or worsening curvature, erectile difficulty, urinary problems or concerns about development. Persistent size-related distress also deserves support, even when measurements are typical. A clinician can assess technique, anatomy and symptoms together.
A statistical comparison should not become a target that determines self-worth. For related concerns, read about penis size and self-esteem and common penis-size myths. The wider penis size guide connects measurement, development and psychology.
Quick answers about average penis size
Is 5 inches an average erect length?
Five inches is 12.7 cm, close to the 2015 pooled mean of 13.12 cm. It is below the 2023 pooled mean of 13.93 cm. The small difference from a study mean does not establish a health problem.
Is 6 inches above average?
Six inches is 15.24 cm, above the erect-length means in both cited reviews. Above average does not mean better function, and length should not be confused with girth.
What is average penis girth?
The 2015 review reported average erect girth of 11.66 cm (4.59 inches). Girth measures circumference, not diameter; the 2023 length review does not provide a replacement girth estimate.
References and evidence limits
Veale D et al. (2015). Am I normal? BJU International. doi:10.1111/bju.13010. Source for the five measurement means, samples and standard deviations. The intervals above are FBU calculations from those data.
Belladelli F et al. (2023). Worldwide Temporal Trends in Penile Length. World Journal of Men’s Health. doi:10.5534/wjmh.220203. Source for the newer erect-length estimate. This review covers length; it should not be used to infer average girth.
Hatipoğlu N and Kurtoğlu S (2013). Micropenis: Etiology, Diagnosis and Treatment Approaches. doi:10.4274/Jcrpe.1135. Source for stretched-length diagnostic criteria and assessment.
Evidence checked: 11 October 2026. This article synthesizes published research for education. It is not an individual examination or a substitute for clinical assessment.
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