BMI Calculator

Calculate your Body Mass Index using weight and height.

Body Mass Index (BMI)

Quick Overview

BMI (Body Mass Index) is a screening measurement based on weight and height. Use this calculator to estimate your BMI and identify your weight category.

Looking for more information? The BMI Guide in the Related Guides section below explains BMI categories, formulas, limitations, and interpretation in greater detail.

Calculate your body mass index

Understanding BMI

How BMI Is Calculated

BMI is calculated from weight and height using standard metric or imperial formulas. The calculator automatically performs the conversion and calculation for you.

How to Interpret BMI

BMI results are grouped into standard categories such as underweight, normal weight, overweight, and obesity. While useful for categorizing weight status, BMI does not directly measure body fat or muscle mass.

Frequently Asked Questions

What is BMI?

BMI (Body Mass Index) is a number calculated from your height and weight that helps classify weight status as underweight, normal weight, overweight, or obesity. It’s a simple and widely used way to assess weight relative to height.

What are the BMI categories?

BMI is classified into different categories:
- Underweight: Less than 18.5
- Normal weight: 18.5 - 24.9
- Overweight: 25 - 29.9
- Obesity: 30 and above.

Note: BMI is a guideline and unitless – it does not directly measure body fat or muscle mass.

Is BMI accurate?

BMI is a useful guideline for assessing body weight relative to height, but it’s not perfect. It does not directly measure body fat or muscle mass, so athletes or very muscular people may appear “overweight” despite being healthy. Use BMI as a quick reference, alongside other measurements like body fat percentage and waist size, to get a more complete picture of your health.

What is the difference between BMI and body fat percentage?

BMI shows how heavy you are for your height, while body fat percentage shows how much of your body is fat.

BMI is a basic calculation based only on height and weight. It compares body weight to height, but it does not measure body fat. Because of this, muscular individuals may be classified as overweight, while people with lower muscle mass and higher fat levels may appear normal.

Body fat percentage focuses directly on body fat and provides a clearer picture of body composition. Methods such as the Navy and RFM formulas estimate body fat using body measurements like waist, neck, height, and sometimes hips.