For children and young people aged 2 to 18, the BMI calculator takes into account age and gender as well as height and weight.
Overweight children are thought to be at increased risk of a variety of health conditions, and they’re also more likely to be overweight as adults.
The BMI calculator works out if a child or young person is:
- underweight – on the 2nd centile or below
- healthy weight – between the 2nd and 91st centiles
- overweight – 91st centile or above
- very overweight – 98th centile or above
A child’s BMI is expressed as a “centile” to show how their BMI compares with children who took part in national surveys.
For example, a girl on the 75th centile is heavier than 75 out of 100 other girls her age.
Measuring waist size is not routinely recommended for children because it does not take their height into account.
See a GP if you’re concerned about your child’s weight. They may be able to refer you to your local healthy lifestyle programme for children, young people and families.
Find out more in underweight children aged 6 to 12 and very overweight children.
Get tips on how to encourage your child to be more active and eat well