Calculate your Body Mass Index and find your healthy weight range
BMI Categories
WHO adult categories (age 20+). Not valid for children or pregnancy. For South Asian adults, health risk rises at lower BMI (WHO Asia-Pacific guidance: overweight from 23, obese from 25). BMI does not distinguish muscle from fat.
How it works
Body Mass Index estimates how a person's weight relates to their height. It is a screening tool for underweight, normal-range, and overweight categories, not a direct measure of body fat.
BMI = weight(kg) / height(m)² (metric) BMI = 703 × weight(lb) / height(in)² (imperial)
weightbody mass in kg (or lb for imperial)heightstanding height in m (or in for imperial)
- 1.75² = 3.0625
- 70 / 3.0625 = 22.86
- WHO categories: <18.5 underweight, 18.5-24.9 normal, 25-29.9 overweight, ≥30 obese.
- BMI misclassifies muscular athletes as overweight and can misread healthy body composition in the elderly.
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Frequently Asked Questions
BMI (Body Mass Index) is calculated by dividing your weight in kilograms by your height in meters squared: BMI = weight(kg) / height(m)². It is a screening tool for body fat categories.
Underweight: below 18.5, Normal weight: 18.5-24.9, Overweight: 25-29.9, Obese: 30 and above. These ranges apply to adults aged 20 and older.
BMI does not directly measure body fat. Athletes with high muscle mass may have a high BMI without excess fat. It also does not account for age, sex, bone density, or fat distribution.
For children and teens (ages 2-19), BMI is calculated the same way but compared to growth charts by age and sex, and expressed as a percentile rather than a fixed category.
Both give the same result. In imperial, the formula is BMI = (weight in pounds × 703) / (height in inches)². This calculator supports both unit systems.