BMI calculator
Work out your body mass index (BMI) and the healthy weight range for your height. Use it as a rough guide: BMI does not know how much of your weight is muscle.
How BMI is calculated
BMI is your weight in kilograms divided by your height in metres squared. For example, 70 kg at 1.75 m gives 70 ÷ (1.75 × 1.75) = 22.9.
What the numbers mean
| BMI | Category (WHO, adults) |
|---|---|
| Below 18.5 | Underweight |
| 18.5–24.9 | Healthy weight |
| 25–29.9 | Overweight |
| 30 or more | Obesity |
Some health services use lower cut-offs for people of South Asian, Chinese and other Asian backgrounds, for example 23 instead of 25 for an increased health risk, because risk rises at a lower BMI.
The limits of BMI
- Muscle: muscular people can have a high BMI with little body fat.
- Fat distribution: fat around the waist matters more for health. A waist measurement under half your height is a useful extra check.
- Age and body type: BMI does not account for age, sex or frame.
- Not for children or pregnancy: children use age-specific charts.
Use BMI as one rough signal, not a verdict. How you feel, how strong you are, your waist size and checks with your doctor matter more.
What to do with your result
If you want to change your weight, our calorie calculator gives you a daily target with a safe pace, and our weight-loss training guide shows how training fits in. If your BMI is below 18.5 or above 30, it is worth talking to your doctor.
General fitness information, not medical advice. Check with your doctor before starting if you have a health condition, an injury or are pregnant, and stop if an exercise causes pain.