BMI Calculator
Metric and imperial BMI
If you're looking to estimate your body fat percentage based on your measurements, try our Body Fat Calculator.
Your BMI
16 18.5 25 30 40
This tool provides estimates only. Consult a healthcare professional for medical advice.
How it works
Enter your height and weight in either metric (kg/m) or imperial (lbs/ft/in) units. The calculator shows your BMI number, which category you fall into, and your healthy weight range.
BMI = weight (kg) / height (m)²
BMI = 703 × weight (lb) / height (in)²
BMI categories
- Underweight: below 18.5
- Normal weight: 18.5–24.9
- Overweight: 25–29.9
- Obese Class I: 30–34.9
- Obese Class II: 35–39.9
- Obese Class III: 40+
Limitations of BMI
BMI was developed in the 1830s by Belgian statistician Adolphe Quetelet as a population-level statistical tool, not as an individual health diagnostic. It has well-known blind spots:
- Muscle mass: Athletes and muscular individuals often read as overweight or obese despite low body fat, since muscle is denser than fat.
- Age and sex: Older adults tend to carry more fat at the same BMI; women naturally carry more fat than men at the same BMI.
- Ethnicity: Health risks associated with BMI levels differ across ethnic groups. Some guidelines recommend lower thresholds for South and East Asian populations.
- Fat distribution: BMI says nothing about where fat is stored. Abdominal fat carries higher cardiovascular risk than fat stored elsewhere.