What is BMI?
Body Mass Index (BMI) is a numerical value calculated from a person's weight and height. It provides a simple measure to categorize individuals as underweight, normal weight, overweight, or obese.
When to Use BMI Calculator
BMI calculations are valuable in the following scenarios:
- Health assessments to identify potential weight-related health risks
- Population studies to track weight trends across different demographics
- Personal weight management goals to establish a baseline and track progress
How to Calculate BMI
The BMI formula varies depending on the measurement system used:
Metric Units: BMI = weight (kg) / height² (m²)
Imperial Units: BMI = 703 × weight (lb) / height² (in²)
BMI Categories
| BMI Range | Weight Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 - 24.9 | Normal weight |
| 25.0 - 29.9 | Overweight |
| 30.0 and above | Obesity |
BMI Calculation Example
Let's calculate the BMI for someone who weighs 70 kg and is 1.75 m tall:
BMI = 70 / (1.75 × 1.75) = 70 / 3.0625 = 22.86
With a BMI of 22.86, this person falls within the normal weight category.
BMI Limitations
BMI doesn't distinguish between muscle and fat mass. Athletes or muscular individuals may have a high BMI despite having healthy body composition. BMI may not be suitable for children, elderly, pregnant women, or certain ethnic groups.