BMI Calculator

Calculate your Body Mass Index (BMI) to determine if you are underweight, normal weight, overweight, or obese.

Calculator

Formula

weight / (height * height)

Explanation

The BMI formula is weight in kilograms divided by height in meters squared (kg/m²). For people who measure their height in centimeters and weight in kilograms, you need to convert the height from centimeters to meters by dividing by 100 before calculating the BMI. For those using imperial units (pounds and inches), the formula is weight in pounds times 703, divided by height in inches squared.

Origin

The Body Mass Index (BMI) was developed by Belgian mathematician, astronomer, and statistician Adolphe Quetelet in the early 19th century (between 1830 and 1850). It was originally known as the Quetelet Index before being termed the Body Mass Index in 1972 by Ancel Keys. Quetelet was attempting to develop a simple measure to quantify the level of obesity in the general population to assist government in allocating resources.

Frequently Asked Questions

What is a healthy BMI range?

A healthy BMI range is generally considered to be between 18.5 and 24.9. Below 18.5 is classified as underweight, 25-29.9 is overweight, and 30 or above is obese.

Is BMI accurate for everyone?

BMI is not perfect and has limitations. It doesn't distinguish between muscle and fat, so athletes with high muscle mass might have a high BMI without being overweight. Similarly, elderly people who have lost muscle mass might have a normal BMI despite having excess fat.

How often should I calculate my BMI?

It's reasonable to check your BMI when you have significant weight changes or annually during regular check-ups. However, it should be used as one of many health indicators, not the only one.

Does BMI apply to children?

For children and teens, BMI is age and sex-specific and is often referred to as BMI-for-age. Growth charts are used to compare a child's measurements with other children of the same age and sex.

What should I do if my BMI is outside the healthy range?

If your BMI falls outside the healthy range, consider consulting a healthcare professional. They can provide personalized advice based on your overall health, body composition, and lifestyle factors.

About This Calculator

The Body Mass Index (BMI) is a measurement of body fat based on height and weight that applies to adult men and women. It is widely used as a general indicator of whether a person has a healthy body weight for their height. A normal BMI ranges from 18.5 to 24.9. A BMI below 18.5 is considered underweight, while a BMI between 25 and 29.9 is considered overweight. A BMI of 30 or higher is classified as obese.

Category: Health

Created by: Dr. Sarah Johnson

Tested By

Dr. Sarah Johnson

Calculator Specialist

Dr. Sarah Johnson is a certified nutritionist with over 15 years of experience in health and wellness. She specializes in weight management and has helped thousands of patients achieve their health goals through personalized nutrition and lifestyle plans.