BMI Calculator
Work out your body mass index in metric or imperial units, see which WHO category it falls in, and the healthy weight range for your height.
For adults aged 18 and over. BMI is a screening measure, not a diagnosis.
Your BMI
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BMI categories for adults
Underweight: below 18.5. Healthy weight: 18.5 to 24.9. Overweight: 25 to 29.9. Obesity: 30 and above, split into class I (30–34.9), class II (35–39.9) and class III (40+).
Waist size, activity level and family history matter too. If your BMI is outside the healthy range, a doctor can tell you what it means for you.
Frequently asked questions
How is BMI calculated?
BMI is your weight in kilograms divided by your height in meters squared. For 70 kg and 1.75 m: 70 ÷ (1.75 × 1.75) = 22.9.
What is a healthy BMI?
For adults, the World Health Organization classes 18.5 to 24.9 as a healthy weight, 25 to 29.9 as overweight and 30 or more as obesity. Some health services use lower thresholds for people of Asian descent.
Is BMI accurate for everyone?
No. BMI doesn’t distinguish muscle from fat, so athletes can score high, and it isn’t meant for children, teenagers or pregnant women. Treat it as a screening number and talk to a doctor about your health.