What is BMI?
The Body Mass Index (BMI) is a measure used to determine whether a person has a healthy body weight for a given height. It is calculated by dividing a person's weight in kilograms by the square of their height in meters.
While BMI is not a perfect measure of health (it doesn't account for muscle mass or bone density), it is a widely used screening tool to identify possible weight problems for adults.
How is BMI Calculated?
The core formula depends on the measurement system you use:
Metric Formula
BMI = kg / m²Imperial Formula
BMI = 703 × lbs / in²BMI Weight Categories
According to the World Health Organization (WHO), typical BMI values are categorized as follows:
- UnderweightLess than 18.5
- Normal Weight18.5 – 24.9
- Overweight25.0 – 29.9
- Obesity30.0 or greater
Limitations of BMI
BMI is a simple tool and does not measure body fat directly. It may categorize a muscular athlete as "overweight" or a person with low muscle mass as "normal weight". It should be used as one of many tools to assess health.