Work out your BMI (body mass index) in kilograms and centimetres or pounds and feet. You also get your weight category, the healthy weight range for your height, and how many kilos you are above or below it. You can switch to the lower BMI cut-offs recommended for South Asian and other Asian adults.
BMI formula
Worked example
A person who is 170 cm tall and weighs 70 kg has a BMI of 70 / 1.70² = 70 / 2.89 = 24.2. That is in the healthy range on the WHO scale, but counts as overweight on the Asian scale, where overweight starts at 23. A healthy weight for 170 cm is about 53.5 to 72 kg (WHO) or 53.5 to 66 kg (Asian cut-offs).
BMI categories for adults
| Category | WHO BMI | Asian BMI |
|---|---|---|
| Underweight | below 18.5 | below 18.5 |
| Healthy weight | 18.5 – 24.9 | 18.5 – 22.9 |
| Overweight | 25 – 29.9 | 23 – 27.4 |
| Obesity | 30 and above | 27.5 and above |
Limits of BMI
BMI does not tell fat from muscle, so very muscular people can show as overweight. It is also less accurate for older adults and pregnant women, and children need age- and sex-specific BMI charts instead. Waist size and body fat percentage add useful detail.
For general information only, not medical advice. Talk to a doctor or registered dietitian before major changes to your diet or training, especially if you are pregnant, under 18, or have a health condition.
Frequently asked questions
How is BMI calculated?
Divide your weight in kilograms by your height in metres squared. In pounds and inches, multiply weight by 703 and divide by height in inches squared.
What is a healthy BMI?
18.5 to 24.9 for most adults. For South Asian and other Asian adults, many health bodies use 18.5 to 22.9 because health risks rise at a lower BMI.
Why are the Asian BMI cut-offs lower?
Studies show Asian populations tend to carry more body fat and develop type 2 diabetes and heart disease at lower BMIs, so WHO suggested lower action points.
Is BMI accurate for athletes?
Not always. Muscle is dense, so athletes can have a high BMI with low body fat. A body fat test is better for them.
Can I use this BMI calculator for children?
No. Children and teenagers need BMI-for-age percentile charts, because healthy BMI changes as they grow.
Related tools
Free educational tool by HawkInc. Results are calculated in your browser and rounded for display; check critical work by hand or with a second method.