BMI Calculator
Use this free BMI calculator to estimate your Body Mass Index, BMI category, healthy weight range and BMI Prime.
Body mass index calculator
What Is BMI?
Body Mass Index, or BMI, is a simple number calculated from height and weight. It is commonly used as a broad screening tool to place adult weight into categories such as underweight, normal weight, overweight and obesity.
BMI is easy to calculate and useful for population-level screening, but it does not directly measure body fat, muscle mass or health status.
Adult BMI Categories
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5–24.9 | Normal weight |
| 25.0–29.9 | Overweight |
| 30.0 and above | Obesity |
BMI Formula
Metric BMI formula: BMI = weight in kilograms ÷ height in meters squared.
Imperial BMI formula: BMI = 703 × weight in pounds ÷ height in inches squared.
Healthy Weight Range
The calculator estimates the weight range corresponding to a BMI of 18.5 to 24.9 for your height. This is a general screening range, not a personal medical target.
Limitations of BMI
BMI may be misleading for athletes, people with high muscle mass, older adults, pregnant people and individuals with unusual body composition. It should not be used as a diagnosis by itself.
BMI Calculator FAQ
Is BMI accurate?
BMI is useful as a broad screening estimate, but it does not directly measure body fat or health.
What is BMI Prime?
BMI Prime compares your BMI to the upper end of the normal adult BMI range, which is 25.
Should athletes use BMI?
Athletes with high muscle mass may have a high BMI without having high body fat, so BMI should be interpreted carefully.