Body Mass Index (BMI) is one of the most widely used health metrics, but it’s also one of the most misunderstood. Let’s break down what BMI actually measures, how to interpret your number, and when you should look beyond it.

What Is BMI?

BMI is a simple calculation that uses your height and weight to estimate body fat:

BMI = weight (kg) ÷ height² (m²)

For imperial units: BMI = (weight in lbs × 703) ÷ height² (inches²)

BMI Categories

Category	BMI Range
Underweight	Below 18.5
Normal weight	18.5 – 24.9
Overweight	25.0 – 29.9
Obese	30.0 and above

Limitations of BMI

BMI doesn’t distinguish between muscle and fat mass. This means:

Athletes may have a high BMI due to muscle mass, not excess fat
Older adults may have normal BMI but high body fat percentage
Pregnant women should not use standard BMI charts

When BMI Is Useful

Despite its limitations, BMI is a helpful screening tool for:

Identifying potential weight-related health risks
Tracking population-level trends
Starting a conversation with your healthcare provider

Calculate Your BMI

Use our free BMI Calculator to find your BMI and see which category you fall into. It supports both metric and imperial units.