Free tools
BMI calculator.
Work out your body mass index with the adult cut-offs used in Australia, and see why it misreads people who lift.
How it works
Weight over height squared.
BMI = weight (kg) ÷ height (m)²
Example: 80 kg at 1.80 m is 80 ÷ 3.24 = 24.7.The ranges are the World Health Organization's adult cut-offs, which the Australian Institute of Health and Welfare and healthdirect use: under 18.5 underweight, 18.5 to 24.9 healthy weight, 25 to 29.9 overweight, and 30 or more obesity.
Limits
- It can't tell muscle from fat. People who carry a lot of muscle often land in the overweight range at a healthy body fat.
- For adults only. Children and teenagers are assessed on age and sex charts.
- Not for pregnancy.
- The NHMRC notes a range of 22 to 27 may suit people over 70, and that healthy ranges differ for some ethnic groups.
- Waist size is a useful second check: the AIHW counts risk as increased from 94 cm for men and 80 cm for women.
Sources
- Australian Institute of Health and Welfare. Overweight and obesity.
- healthdirect Australia. BMI calculator.
- NHMRC and NZ Ministry of Health. Nutrient Reference Values for Australia and New Zealand: Dietary energy, 2006.