BMI calculator
BMI calculator: body mass index and healthy weight range
Body mass index (BMI) is your weight in kilograms divided by your height in metres squared. This BMI calculator shows your category under the WHO adult ranges, the cut-offs suggested for Asian populations and the weight range that matches a healthy BMI for your height. BMI is a screening number, not a diagnosis.
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Use the BMI calculator
How do I calculate BMI?
Divide your weight in kilograms by your height in metres squared. For example, 70 kg at 1.70 m is 70 divided by 2.89, which is about 24.2. In pounds and inches, multiply weight by 703 and divide by height in inches squared. The calculator above does either for you.
| BMI (kg/m²) | WHO adult category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 to 24.9 | Normal weight |
| 25.0 to 29.9 | Overweight |
| 30.0 to 34.9 | Obesity class I |
| 35.0 to 39.9 | Obesity class II |
| 40.0 and above | Obesity class III |
What is a healthy BMI?
For most adults the WHO lists 18.5 to 24.9 as the normal weight range. For Asian populations, a WHO expert consultation suggested additional action points at 23 and 27.5 because health risks can rise at lower BMI. Your own healthy range depends on build, age and health, so treat it as a guide.
Is BMI accurate?
BMI is a quick screening number, not a measure of body fat. It can read high for muscular people and low for people who have lost muscle, and it does not show where fat is stored. It is not meant for children, pregnant women or competitive athletes. Use it alongside waist size and a conversation with a professional.
To estimate body fat, try the body fat calculator.
What weight is healthy for my height?
The healthy weight range is the weight that gives a BMI of 18.5 to 24.9 at your height. At 1.70 m, that is roughly 53.5 to 72 kg. The calculator above works it out for you, in kilograms and pounds, and shows how far you are from the range. It is a guide, not a target everyone must reach.
See also the ideal weight calculator and calorie calculator.
Log what you eat in the app
A target only helps if you know what you eat. AI Calorie estimates calories and macros from a photo or a short description. It is free to start with daily limits: see pricing. This calculator is not medical advice; see medical review.
Sources
- World Health Organization. Obesity: preventing and managing the global epidemic. WHO Technical Report Series 894; 2000. (Adult BMI categories.)
- WHO Expert Consultation. "Appropriate body-mass index for Asian populations and its implications for policy and intervention strategies." Lancet 2004;363(9403):157-163.
AI Calorie gives general nutrition information and AI-generated estimates. It is not medical advice. See medical review and our Terms of Use.