Calculate your Body Mass Index — free, instant
Enter your height and weight to calculate your BMI, see your weight category, ideal weight range, and what weight would put you in the healthy BMI range.
weight Normal Over-
weight Obese
| Category | BMI Range | Health Risk |
|---|---|---|
| Underweight | Below 18.5 | Moderate |
| Normal weight | 18.5 – 24.9 | Low |
| Overweight | 25.0 – 29.9 | Increased |
| Obese Class I | 30.0 – 34.9 | High |
| Obese Class II | 35.0 – 39.9 | Very High |
| Obese Class III | 40.0 and above | Extremely High |
What is BMI and how is it calculated?
Body Mass Index (BMI) is a measure of body fat based on height and weight. It's calculated by dividing weight in kilograms by height in meters squared. In imperial units: (weight in lbs × 703) ÷ (height in inches)².
BMI formula
Metric: kg ÷ m². Imperial: (lbs × 703) ÷ inches². Both give the same result expressed as a dimensionless number.
BMI Prime
BMI Prime is your BMI divided by 25 (the upper limit of normal). A BMI Prime of 1.0 or less is considered healthy. Above 1.0 means overweight or obese.
Limitations of BMI
BMI doesn't distinguish between muscle and fat mass. Athletes may have a high BMI but low body fat. The elderly may have a healthy BMI but high body fat percentage.
Ideal weight (Hamwi method)
For men: 106 lbs for 5 feet, plus 6 lbs per inch above 5 feet. For women: 100 lbs for 5 feet, plus 5 lbs per inch above 5 feet.