Doctors searched through 17 published studies studies on more than 15,000 men who had their penis size measured by a health professional and graphed the averages in Tuesday's issue of BJU International, formerly the British Journal of Urology.
The graphs will help doctors reassure the large majority of men that their penis size is in the normal range, said study author Dr. David Veale, of King's College London.
For men with small penis anxiety, education and counselling may be helpful, Veale and his team said.
"It is a hidden problem," Veale said in an email. "Men are more likely to seek solutions on the internet with lotions potions, extenders or surgery."
Some men who are preoccupied and severely distressed with the size or shape of their penis may be diagnosed with body dysmorphic disorder, one of Veale's specialities.
The researchers say measuring penis size is important in assessing men who complain of a small penis and to investigate the relationship between condom failure and penile dimensions.
The average measurements were:
- Flaccid stretched length 13.24 cm.
- Erect length 13.12 cm.
- Flaccid girth or circumference 9.31 cm.
- Erect circumference 11.66 cm.
Stretched flaccid length looks to be an excellent estimate of erect penile length, they said.
The reviewers recommended taking the measurements in a private, air-conditioned consulting room using a disposable tape measure.
Flaccid circumference is measured mid-shaft, length is skin to tip and bone to tip.
One of the limitations is relatively few erect measurements have been clinically done. Study volunteers may also have been more confident in their penis size than the general male population.
In 2006, the reviewers noted a large internet survey of heterosexual men and women suggested 85 per cent of women were satisfied with their partner's penis size and 55 per cent of men were satisfied with their own size. The preferences may differ in the homosexual community, the researchers said.
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