Due to natural variation, individuals pass through the Tanner stages at different rates, depending in particular on the timing of puberty. In HIV treatment, the Tanner scale is used to determine which treatment regimen to follow (adult, adolescent, or pediatric).
prepubertal (testicular volume less than 1.5 ml; small penis of 3 cm or less) [typically age 9 and younger]
testicular volume between 1.6 and 6 ml; skin on scrotum thins, reddens and enlarges; penis length unchanged [9-11]
testicular volume between 6 and 12 ml; scrotum enlarges further; penis begins to lengthen to about 6 cm [11-12.5]
testicular volume between 12 and 20 ml; scrotum enlarges further and darkens; penis increases in length to 10 cm and circumference [12.5-14]
testicular volume greater than 20 ml; adult scrotum and penis of 15 cm in length [14+]
Illustration of the Tanner scale for females.
no glandular tissue: areola follows the skin contours of the chest (prepubertal) [typically age 10 and younger]
breast bud forms, with small area of surrounding glandular tissue; areola begins to widen [10-11.5]
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 [11.5-13]
increased breast size and elevation; areola and papilla form a secondary mound projecting from the contour of the surrounding breast [13-15]
breast reaches final adult size; areola returns to contour of the surrounding breast, with a projecting central papilla. [15+]
Pubic hair (both male and female)
no pubic hair at all (prepubertal state) [typically age 10 and younger]
small amount of long, downy hair with slight pigmentation at the base of the penis and scrotum (males) or on the labia majora (females) [10–11.5]
hair becomes more coarse and curly, and begins to extend laterally [11.5–13]
adult-like hair quality, extending across pubis but sparing medial thighs [13–15]|
hair extends to medial surface of the thighs [15+]
The scale has been criticized by the pornography industry for its potential to lead to false child pornography convictions, such as in the case when government experts used it to assert that pornographic actress Lupe Fuentes was underage. Fuentes personally appeared at the trial and provided documentation that showed that the DVDs in question were legally produced. The author of the classification system himself has argued that age classification using the Tanner stages represents invalid use. Tanner stages do not match with chronological age, but rather maturity stages and thus are not diagnostic for age estimation.