Use this Peak Height Velocity Estimator to get a rough idea of where a child is in the puberty growth spurt — based on age, sex, and commonly tracked physical signs. It compares your inputs against published population averages for the timing and speed of the adolescent growth spurt.
What Is Peak Height Velocity?
Peak height velocity (PHV) is the single fastest point of the puberty growth spurt — the moment during adolescence when a child is gaining height faster than at any other time after infancy. Growth velocity slows gradually through mid-childhood, dips to its lowest point right before puberty (sometimes called the "preadolescent dip"), then accelerates sharply, peaks, and decelerates again as the growth plates approach fusion.
PHV happens earlier and is less intense in girls than in boys. On average, girls reach PHV around age 11.5, gaining roughly 8.3 cm in that peak year, while boys reach PHV about two years later, around age 13.5, gaining roughly 9.5 cm in that peak year. Because boys grow for a longer stretch before puberty and add slightly more height during their spurt, this timing difference is the main reason adult men are, on average, taller than adult women.
How This Estimator Works
1. Age comparison. Current age is compared against the published average ages for growth spurt takeoff, peak height velocity, and completion for the selected sex.
2. Sign checklist. Reported physical signs are scored against research linking specific pubertal (Tanner) stages to the likelihood of having already reached PHV.
3. Combined estimate. Both signals are combined into one of five general phases, from "Pre-Spurt" to "Decelerating" — signs are weighted more heavily, since they reflect the individual child rather than a population average.
4. Safety flags. Ages and sign combinations outside the typical range for precocious or delayed puberty are flagged for a conversation with a pediatrician.
Typical Puberty Growth Timeline
| Milestone | Girls (average) | Boys (average) |
|---|
| Growth spurt "takeoff" begins | ~9 years | ~11 years |
| Peak height velocity (PHV) | ~11.5 years | ~13.5 years |
| Peak growth rate | ~8.3 cm/year | ~9.5 cm/year |
| Total height gained during puberty | ~27–29 cm | ~30–31 cm |
| Linear growth essentially complete | ~15 years | ~17 years |
PHV happens earlier in puberty than most parents expect. Research tracking Tanner stages alongside growth found that most girls reach PHV by Tanner breast stage 3 — often before their first period — and most boys reach PHV by Tanner genital stage 4. In girls specifically, about 7 in 10 reach PHV before menarche, meaning the fastest growth is usually already behind them by the time periods start.
Signs Often Seen Around Peak Height Velocity
Girls — often near or approaching PHV: Breast development combined with pubic hair growth, but periods have not yet started.
Girls — often past PHV: Menstrual periods have started. Growth usually continues for a couple more years but at a steadily decreasing rate.
Boys — often near or approaching PHV: Genital growth and pubic hair are underway and the voice is beginning to change.
Boys — often past PHV: Facial hair has started appearing. This tends to emerge later in puberty, after the fastest growth has already occurred.
When Timing Falls Outside the Typical Range
Precocious (early) puberty: Defined as any sign of puberty appearing before age 8 in girls or age 9 in boys. Most cases are benign variants, but it is worth a pediatric evaluation to rule out an underlying cause.
Delayed puberty: Defined as no signs of puberty by age 13 in girls or age 14 in boys. Most commonly this reflects a normal "constitutional delay" that runs in families, but it is still worth discussing with a pediatrician.
These thresholds flag when to seek an evaluation — they are not, by themselves, a diagnosis of any condition.
Limitations of This Estimator
Self-reported signs are approximate. Formal Tanner staging is done by a clinician; a parent-reported checklist is a rough proxy, not a substitute.
Individual variation is wide. PHV can occur years earlier or later than the population average in perfectly healthy children.
No bone age or growth chart data used. Tools like bone age X-rays and serial height measurements over time give a far more precise picture than age and signs alone.
Not for medical decisions. This tool is educational. Concerns about growth or pubertal timing should always go through a pediatrician.
Frequently Asked Questions
What is peak height velocity?
It's the fastest point of the puberty growth spurt — the single year a child gains height quicker than at any other time after infancy.
Does PHV happen before or after periods start in girls?
Usually before. Most girls reach PHV around Tanner breast stage 2–3, and roughly 7 in 10 have already passed their peak by the time periods begin.
Why do boys grow taller than girls on average?
Boys start puberty about two years later than girls, giving them more pre-pubertal growing time, and their peak growth rate is slightly higher — together this adds up to a taller average adult height.
References
2
Growth and pubertal development in children and adolescents: effects of diet and physical activity
Rogol AD, Clark PA, Roemmich JN. American Journal of Clinical Nutrition. 2000;72(2 Suppl):521S–528S
pubmed.ncbi.nlm.nih.gov/10919954
3
Relationship Between Timing of Peak Height Velocity and Pubertal Staging in Boys and Girls
Granados A, Gebremariam A, Lee JM. Journal of Clinical Research in Pediatric Endocrinology. 2015;7(3):235–237
pubmed.ncbi.nlm.nih.gov/26831559
4
Disorders of Puberty: An Approach to Diagnosis and Management
Klein DA, Emerick JE, Sylvester JE, Vogt KS. American Family Physician. 2017;96(9):590–599
pubmed.ncbi.nlm.nih.gov/29094880
