A growth percentile shows how your child compares to other children of the same age and sex. A child on the 50th percentile for height is taller than 50% of children their age and shorter than the other 50%. The 75th percentile means taller than 75% of peers. Any measurement between the 2nd and 98th centile is generally within the healthy range for UK children.

The NHS uses the UK-WHO growth charts, which are based on World Health Organization (WHO) Child Growth Standards combined with British 1990 growth reference data for older children. These are included in the Personal Child Health Record (the Red Book) and are the standard reference used by all UK health visitors, GPs and paediatricians.

Any measurement between the 2nd and 98th centile is considered within the normal healthy range. NHS guidance suggests speaking to your GP or health visitor if your child’s measurement falls below the 0.4th centile (the lowest line on the Red Book chart), or if measurements cross two or more major centile lines downward over a period of months. A single measurement is far less informative than tracking growth over time.

Adult BMI uses fixed thresholds (e.g. 18.5–25 is healthy). Child BMI — also called BMI-for-age — is age and sex specific, because a child’s body composition changes as they grow. A 5-year-old and a 12-year-old with the same BMI number are in very different positions on their respective charts. In the UK, a BMI above the 91st centile may indicate overweight; above the 98th may indicate obesity; and below the 2nd centile may indicate underweight.

Speak to your GP or health visitor if: your child’s height or weight falls below the 0.4th centile; measurements drop across two or more major centile lines over several months; your child suddenly stops growing or loses weight; you notice a significant difference between height and weight centiles; or you have general concerns about your child’s growth or development. This calculator is for information only and is not a substitute for professional advice.

For babies under 1, monthly measurements are typical at health visitor checks. For toddlers aged 1–2, quarterly checks are common. For children over 2, annual measurements are usually sufficient unless there is a concern. In the UK, growth is routinely checked at the 6-week check, 12-month review, and 2–2.5 year check. Many schools also measure children in Reception (age 4–5) and Year 6 (age 10–11) as part of the National Child Measurement Programme.

Mid-parental height is a standard method for estimating likely adult height. For boys: (Father’s height + Mother’s height + 13 cm) ÷ 2. For girls: (Father’s height + Mother’s height − 13 cm) ÷ 2. This gives a target range of ±10 cm. It’s an estimate only — genetics provide the blueprint but nutrition, health, sleep and other factors all influence final height. Enter both parents’ heights above to see this estimate in your results.

At 2 years: boys average ~88 cm, 12.5 kg; girls ~87 cm, 12 kg. At 5 years: boys ~110 cm, 18.5 kg; girls ~109 cm, 18 kg. At 10 years: boys ~138 cm, 32 kg; girls ~140 cm, 33 kg. At 16 years: boys ~174 cm, 63 kg; girls ~163 cm, 57 kg. These are 50th centile values — exactly half of healthy UK children will be above and half below these figures.