Tanner Stages

A system of classification of the progress of puberty, developed in the second half of the twentieth century by Dr. James Tanner, a British pediatrician. A similar set of developmental criteria has been defined for girls, dealing with both breast and genital development. Details are widely available on the web.


The male Tanner Stages illustrated.

Typical testicle volume and fertility Penis
Artist's impression of genitalia (when loosely circumcised) Annual height gain Comments
Stage 1 Under 4 ml

Not fertile at least whilst orgasms, if any, remain dry.
Erections occur spontaneously or by masturbation.

Tight circumcision produces a much shorter shaft that is horizontal when flaccid.
(2696 bytes) 50 - 60 mm If elective circumcision is chosen on parental initiative, it is best done no later than Tanner Stage 1.

Mean age  (and 'normal' range)  at stage boundary:   11.5  (9.5 to 13.5)  years
Stage 2 6 ml

Fertility normally begins during this stage.
First discernible increase in both length and girth. The erect penis may carry at a very high angle, almost touching the abdomen. (2756 bytes) 50 - 60 mm First growth of pubic hair that is evidently different from other body hair. Occasional ejaculation now becomes possible by masturbation.
Mean age  (and 'normal' range)  at stage boundary:   12.4  (10.1 to 14.6)  years
Stage 3 14 ml

Growth continues in both length and girth, partly recovering any shortening that resulted from tight circumcision before puberty. (2897 bytes) 70 - 80 mm Voice breaks. Ejaculation occurs more frequently in wet dreams or by masturbation. This is beneficial in terms of long-term prostate health.
Mean age  (and 'normal' range)  at stage boundary:   14.0  (11.5 to 16.5)  years
Stage 4 20 ml

-- Ditto -- (???? bytes) Peaks circa 100 mm Voice matures.

Underarm hair develops.

Wet dreams frequent in the absence of other sexual activity.
Mean age  (and 'normal' range)  at stage boundary:   16.5  (14.5 to 18.5)  years
Stage 5 28 ml

Modern society tends to defer fatherhood to a later age, but in biological terms this is the lifetime peak of fertility.
Mature size in terms of both length and girth (flaccid and erect) is reached typically five years after crossing the Stage 1 - Stage 2 boundary. (3311 bytes) Growth ceases typically six years after crossing the Stage 1 - Stage 2 boundary. Adult pubic hair distribution.

General adult physique and sexuality.
  • Artwork credit: J. Geoff Malta, MA, EdM

  • Parents wishing to convey the above information to boys approaching puberty will find a simplified, more child-oriented version here: http://www.puberty101.com. The same website also gives age-appropriate information about puberty in girls.

  • Age boundaries have been adjusted from Tanner's original (1960s) work to account for a modern tendency towards earlier puberty. The reasons for this trend are not fully understood.

Watching for signs of abnormality

The wise parent will question any departure from the norm as regards the boundary between Tanner Stages 1 and 2, wary of the possibility of precocious puberty on the one hand or abnormally late development on the other. It used to be the case that such matters were identified at school medicals, but routine genital examinations for all schoolchildren seem to have fallen out of fashion. Note that there are no "whilst clothed" indicators of the boundary between Stage 1 and Stage 2; it really does require stripping off for this milestone to be identified.

A matter for debate

debate-logo (14794 bytes)
How such essential developmental checks are best achieved in our increasingly prudish culture is a matter for debate. Should family nudity be more of a norm? Should traditional school medicals be restored? Should boys routinely be taken to see the family doctor in the absence of any illness? Should mothers still bath their boys at this age? Or should the issue be glossed over, any medical problems remaining untreated due to censorship and embarrassment winning the day?

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