Tanner scale
physical development scale of children, adolescents, and adults
The Tanner scale (also known as the Tanner stages or sexual maturity rating (SMR)) is a scale of physical development as pre-pubescent children transition into adolescence, and then adulthood. The scale defines physical measurements of development based on external primary and secondary sex characteristics, such as the size of the breasts, length of the penis, volume of the testes, and growth of pubic hair. This scale was first quantified in 1969 by James Tanner, a British pediatrician, after a two-decade study following the physical changes in girls undergoing puberty.
Due to natural variation, individuals pass through the Tanner stages at different rates, depending in particular on the timing of puberty. Among researchers who study puberty, the Tanner scale is commonly considered the "gold standard" for assessing pubertal status when it is conducted by a trained medical examiner. In HIV treatment, the Tanner scale is used to determine which regimen to follow for pediatric or adolescent patients on antiretroviral therapy (adult, adolescent, or pediatric guidelines). The Tanner scale has also been used in forensics to determine aging, but its usage has decreased due to lack of reliability.
Stages
Adapted from Adolescent Health Care: A Practical Guide by Lawrence Neinstein.
Genitals (male)
Tanner I
testicular volume less than 1.5 ml; small penis (prepubertal)
Tanner II
testicular volume between 1.6 and 6 ml; skin on scrotum thins, reddens and enlarges; penis length unchanged
Tanner III
testicular volume between 6 and 12 ml; scrotum enlarges further; penis begins to lengthen
Tanner IV
testicular volume between 12 and 20 ml; scrotum becomes larger and darkens; penis further increases in length and starts to increase in breadth
Tanner V
testicular volume at least 20 ml; adult scrotum and penis
Breasts (female)
Tanner I
no glandular tissue: areola follows the skin contours of the chest (prepubertal)
Tanner II
breast bud forms, with small area of surrounding glandular tissue; areola begins to widen
Tanner III
breast begins to become more elevated, and extends beyond the borders of the areola, which continues to widen but remains in contour with surrounding breast
Tanner IV
increased breast sizing and elevation; areola and papilla form a secondary mound projecting from the contour of the surrounding breast
Tanner V
breast reaches final adult size; areola returns to contour of the surrounding breast, with a projecting central papilla
Pubic hair (both male and female)
Tanner I
no pubic hair at all (prepubertal)
Tanner II
small amount of long, downy hair with slight pigmentation at the base of the penis and scrotum (males) or on the labia majora (females)
Tanner III
hair becomes more coarse and curly, and begins to extend laterally
Tanner IV
adult-like hair quality, extending across pubis but sparing medial thighs
Tanner V
hair extends to medial surface of the thighs
Height
During Tanner V, females stop growing and reach their adult height. Usually, this happens in their mid teens at 14 or 15 years for females.
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