Child BMI Calculator
BMI and category for children.
Enter your values
Results update instantly as you type — no submit needed.
Results
- BMI
- 16.8
- Category (approximate)
- Healthy weight
- Typical BMI for age
- 18.7
- Difference from typical
- -1.9
- Healthy weight range
- 31.8–40.4 kg
Quick answer
Children's BMI is interpreted against age and sex percentiles, not the fixed adult cut-offs.
BMI = kg ÷ m²
How to use the Child BMI Calculator
- 1Enter the child's weight in kilograms.
- 2Enter height in centimetres.
- 3Enter their age in years.
Frequently asked questions
Why can't I use adult BMI?
Children's body composition changes with age, so cut-offs shift each year.
Is BMI accurate for athletic kids?
It can overstate fat in muscular children — use it alongside other measures.