Estimate the Tanner stage
The five stages
In the 1960s, James Tanner studied the children of Harpenden in England and described puberty as five stages for each characteristic: breast development (B1 to B5) and pubic hair (PH1 to PH5) in girls, genital development (G1 to G5) and pubic hair in boys. Stage 1 is the prepubertal state; stages 2, 3 and 4 trace the progression; stage 5 is adult maturity. The stages remain the international language for describing puberty, used in every paediatric endocrine clinic in the world.
The stages describe what is visible, not what is happening hormonally, and different characteristics can sit at different stages in the same child. Breast development can be at stage 3 while pubic hair is at stage 2, because they are driven by partly different hormones: gonadarche from the ovaries or testes, adrenarche from the adrenal glands. The overall stage is therefore always a summary, and clinicians record the components separately (for example B3 PH2) rather than forcing a single number.
Typical ages, and what counts as early or late
Puberty typically begins between 8 and 13 in girls (breast buds) and 9 and 14 in boys (testicular enlargement), with menarche usually arriving in stage 4 around age 12 to 13, about two years after puberty starts. The whole progression from stage 2 to stage 5 typically takes about four years, though the range is wide.
Precocious puberty is defined as pubertal development before age 8 in girls or 9 in boys. It matters because early oestrogen or testosterone exposure advances bone age and can compromise final adult height, and because it occasionally signals underlying disease. Delayed puberty is no pubertal development by 13 in girls or 14 in boys, or more than five years from start to completion. Most delayed puberty is constitutional, the late-bloomer pattern that runs in families, but it needs assessment to exclude the pathological causes.
Secular trends have nudged thelarche (breast development) earlier in many populations without much change in menarche timing, which is one reason guidelines emphasise the full picture rather than a single sign.
How the estimate is made
The calculator takes the primary gonadal characteristic (breast or genital stage) and the pubic hair stage, and averages them: the likely stage is the rounded mean, reported as a range when the two disagree. Menarche overrides toward stage 4 to 5, because periods essentially never precede stage 4. Growth pattern and other changes add context notes rather than changing the number.
Age gates add the safety flags: development before 8 (girls) or 9 (boys) triggers the precocious puberty flag; no development by 13 (girls) or 14 (boys) triggers the delayed flag. These are the standard clinical cutoffs, and either one means the young person should be assessed rather than watched indefinitely.
Worked examples
Example 1. A girl answers breast stage 2, pubic hair stage 2, mid growth spurt, age 10. Primary 2, secondary 2: likely stage 2. No flags. This is a typical early puberty picture; routine monitoring is enough.
Example 2. A boy answers genital stage 3, pubic hair stage 4, age 13. Likely stage 4 (rounded mean 3.5), range 3 to 4. Growth spurt fits stages 3 to 4 in boys. No flags.
Example 3. A girl answers breast stage 2, pubic hair stage 1, age 7. Development before age 8 triggers the early puberty flag: this needs paediatric assessment, including bone age and possibly hormone tests, because early oestrogen exposure advances skeletal maturation.
Why self-assessment is only a guide
Studies consistently find that self-assessed Tanner staging agrees with clinical examination only modestly, commonly within one stage. Adolescents tend to overestimate early changes and underestimate later ones, and some distinctions, particularly between stages 2 and 3 of breast or genital development, are genuinely difficult without examination experience.
The questionnaire is therefore a triage and communication tool: it tells a family roughly where things stand and whether the timing flags are raised, so the conversation with the paediatrician starts from an informed place. Definite staging, and any decision about investigating or treating early or late puberty, belongs to clinical assessment with hormone testing and bone age where indicated.
There is also a psychological dimension worth handling well. Puberty arrives with self-consciousness, and questions about bodily changes can feel intrusive. A parent working through this questionnaire with a young person should keep it matter-of-fact, private and unhurried, and make clear that variation is normal. The goal is information and reassurance, and the young person's comfort comes first; any question can be skipped and discussed with the clinician instead.
Key takeaways
- Tanner stages 1 to 5 describe pubertal progression; different characteristics can sit at different stages.
- Puberty typically starts between 8 and 13 in girls and 9 and 14 in boys.
- Development before 8 (girls) or 9 (boys) is precocious; none by 13 or 14 is delayed: both need assessment.
- Menarche usually arrives in stage 4, about two years after puberty starts.
- Questionnaire staging is commonly off by one stage: it guides discussion, not diagnosis.
Frequently asked questions
What is the difference between Tanner stage 2 and 3 for breasts?
Stage 2 is the first change: small firm buds under one or both nipples with slight areola enlargement. Stage 3 is clear enlargement where the breast, nipple and areola form one mound with no separate bump. The distinction can be subtle, which is one reason self-assessment is approximate and clinical examination remains the standard.
My daughter has pubic hair but no breast development. Is that normal?
Often yes. Pubic hair is driven substantially by adrenal androgens (adrenarche), which can start before, with, or after the ovarian changes of breast development (thelarche). Isolated early pubic hair is common and usually benign, but pubic hair before age 8, or with other concerning signs, should be discussed with the paediatrician.
At what stage does the growth spurt happen?
The peak growth spurt comes around stages 3 to 4: roughly stages 2 to 3 in girls (peak around 12) and stages 3 to 4 in boys (peak around 14). Girls do most of their pubertal growing relatively early, which is why late-developing boys can seem to fall behind and then catch up dramatically.
Can Tanner staging be wrong by a lot?
Rarely by more than one stage when the questions are answered carefully, but one stage is a wide band in puberty terms. The stages most often confused are the middle ones. If a decision depends on the exact stage, such as investigating precocious puberty, clinical examination settles it.
Is it normal for one breast to develop before the other?
Yes, very common. Breast buds often appear asymmetrically, sometimes months apart, and usually even out. Persistent marked asymmetry after puberty is complete is worth mentioning to the clinician but is rarely a sign of disease.