Children’s BMI in the UK
In England, the National Child Measurement Programme measures children in Reception and Year 6, and UK services plot BMI on the UK90 centile charts. This calculator uses the CDC 2000 reference, which is very close for most children but can give a slightly different percentile. If you have an NCMP letter, it will show the UK centile.
Healthy habits for kids
Children and young people are advised to be active for an average of at least 60 minutes a day, with activities that strengthen muscles and bones several times a week. Limiting sugary drinks, eating fruit and vegetables at most meals and keeping regular bedtimes all help children grow along a healthy BMI percentile.
Where the BMI index comes from
The formula was described in the 1830s by the Belgian statistician Adolphe Quetelet, who noticed that adult weight rises roughly with the square of height. It was renamed “body mass index” by the physiologist Ancel Keys in 1972, and the World Health Organization adopted today’s cut-offs — 18.5, 25 and 30 — in the 1990s. That long history is why the same index is used by doctors, insurers and researchers around the world.
Babies and toddlers under 2
BMI-for-age charts start at age 2. For babies and toddlers, doctors use weight-for-length charts from the World Health Organization instead, measuring length lying down. If your child is younger than 2, ask your health visitor or paediatrician to plot their growth.