Child Growth Velocity Calculator
Measures how fast a child is currently growing in cm per year and projects an estimated adult height based on that rate. Use it to spot growth slowdowns or spurts between routine check-ups.
About this calculator
Growth velocity is the rate of height gain over a defined period, expressed in centimetres per year. It is calculated as: velocity (cm/yr) = (currentHeight − previousHeight) / (timeInterval / 12). To project an estimated adult height, the calculator assumes the child continues growing at the same annualised rate until age 18 and then adds a sex-specific offset — 10 cm for males and 5 cm for females — to account for the average pubertal height gain that most children experience: Predicted Height = velocity × (18 − currentAge) + currentHeight + sexOffset. Normal velocity benchmarks are approximately 5–6 cm/yr for school-age children, rising to 8–12 cm/yr during the pubertal growth spurt. Persistent velocity below 4 cm/yr warrants evaluation by a paediatrician.
How to use
A 10-year-old boy measured 135 cm six months ago and is now 138 cm. Time interval = 6 months. Velocity = (138 − 135) / (6 / 12) = 3 / 0.5 = 6 cm/yr. Predicted height = 6 × (18 − 10) + 138 + 10 = 6 × 8 + 148 = 48 + 148 = 196 cm. Enter currentHeight = 138, previousHeight = 135, timeInterval = 6, currentAge = 10, gender = male. The result shows a healthy velocity of 6 cm/yr and a projected adult height of 196 cm.
Frequently asked questions
What is a normal growth velocity for a school-age child?
For children aged 4–10 years, a typical growth velocity is 5–6 cm per year. During infancy growth is much faster, often 15–25 cm in the first year, then slowing to 8–10 cm in the second year. The pubertal growth spurt, which peaks around ages 12–13 in girls and 14–15 in boys, can push velocity back up to 8–12 cm/yr. A sustained velocity below 4 cm/yr outside of infancy is a common threshold that prompts further clinical investigation.
How accurate is this predicted adult height calculation?
The formula used here is a simplified linear projection and should be treated as a rough estimate rather than a clinical prediction. It assumes the child will maintain their current growth rate until age 18, which rarely happens in practice due to natural pubertal acceleration or deceleration. More accurate methods, such as the Bayley-Pinneau or Tanner-Whitehouse methods, incorporate bone age from wrist X-rays. This tool is best used to track trends over time rather than to set firm height expectations.
When should I be concerned about my child's growth velocity?
Parents and clinicians should investigate further if a child's annualised growth velocity falls below 4 cm/yr during the school-age years, if there is a significant downward crossing of height percentile lines on a standard growth chart, or if growth appears to have completely stopped outside of normal puberty timing. Potential causes include nutritional deficiencies, chronic illness, hypothyroidism, growth hormone deficiency, or psychosocial factors. A single measurement is never enough — tracking velocity over at least 6 months is needed before drawing conclusions. Consult a paediatric endocrinologist if concerns persist.