BMI (Body Mass Index) is a screening measure based on weight and height: BMI = weight / height².

What are the BMI categories?

Common adult categories: underweight <18.5, normal 18.5–24.9, overweight 25–29.9, obese ≥30.

BMI calculator

Calculate Body Mass Index (BMI) using height and weight (metric or imperial).

Units

Decimals

Weight (kg)

Height (cm)

Result will appear here.

Note: BMI is a screening metric and doesn’t directly measure body fat or health. Consider professional guidance for medical decisions.

What is BMI?

BMI (Body Mass Index) is a simple number based on your height and weight. It’s commonly used as a quick screening tool to categorize weight status in adults. BMI is easy to compute and helps compare body size across populations.

How to calculate BMI

In metric units, BMI is calculated as weight (kg) / height (m)². In imperial units, it’s commonly computed as 703 × weight (lb) / height (in)². This calculator supports both and shows your BMI category using standard adult ranges.

BMI formula

Metric: BMI = kg / m²

Imperial: BMI = 703 × lb / in²

Why use this online BMI calculator?

It’s fast and avoids calculation mistakes when converting centimeters to meters or feet/inches to inches. Use it to track changes over time or for quick checks. If you’re an athlete or have a higher muscle mass, BMI may not reflect body composition accurately.