BMI Calculator
Calculate your Body Mass Index in metric or imperial units, with WHO category and healthy weight range.
Runs in your browser — your data never leaves your device.
About the BMI Calculator
Body Mass Index (BMI) is a quick screening number that compares weight with height. It is widely used by doctors and health organisations as a first check of whether weight may be affecting health.
This calculator shows your BMI, the World Health Organization (WHO) category, and the weight range that would be considered healthy for your height.
BMI is a screening tool, not a diagnosis. It does not separate muscle from fat and is less accurate for athletes, older adults, pregnant women and children. Speak to a doctor for personal advice.
How to use the BMI Calculator
- Choose Metric (kg, cm) or Imperial (lb, feet and inches).
- Enter your weight and height.
- Press Calculate BMI.
Formula
- BMI = weight (kg) ÷ height (m)²
- In imperial units: BMI = 703 × weight (lb) ÷ height (in)²
WHO adult categories: below 18.5 underweight · 18.5–24.9 healthy weight · 25–29.9 overweight · 30 and above obesity.
WHO has also noted that many Asian populations face higher health risk at lower BMI values, so some South Asian guidelines treat 23 and above as overweight.
Examples
- 70 kg and 170 cm: 70 ÷ 1.70² = 24.2 (healthy weight). Healthy range at this height: about 53.5–72.0 kg.
- 90 kg and 175 cm: 90 ÷ 1.75² = 29.4 (overweight).
Frequently asked questions
Is BMI accurate for everyone?
No. BMI does not measure body fat directly. Muscular people can have a high BMI while being healthy, and it is not used the same way for children and pregnant women.
Can I use this BMI calculator for children?
No. Children and teenagers need age- and sex-specific BMI charts. Please ask a doctor.
Is my data stored?
No. The calculation happens in your browser and nothing you enter is sent anywhere.