The Body Mass Index (BMI) is a simple and quick way to estimate the ratio of body weight to height. With our BMI calculator, you can find out in just a few seconds whether you’re within the normal range or if you’re underweight or overweight.
What is the Body Mass Index (BMI)?
BMI is an internationally recognized guideline that helps you better understand your body weight. It is calculated using a simple formula:
BMI = Weight (kg) ÷ (Height in m)²
Here’s an example:
If you weigh 70 kilograms and are 1.75 meters tall, that gives you a BMI of about 22.9—which falls within the normal weight range.
BMI Categories at a Glance
If your BMI is below 18.5, you are considered underweight.
A value between 18.5 and 24.9 corresponds to a normal weight.
If your BMI is between 25 and 29.9, you are considered overweight.
A BMI of 30 or higher is classified as obesity .
This classification is based on recommendations from the World Health Organization (WHO) and provides you with a general guide to assessing your current weight.
What BMI Tells You—and What It Doesn’t
BMI is a helpful guideline, but not a medical diagnosis. It does not take into account your body composition—that is, how much muscle mass, fat, or water you have.
If you exercise regularly and have built up a lot of muscle mass, your BMI may be slightly higher, even though you’re very fit. That’s why you should always consider your BMI in conjunction with other factors, such as your body fat percentage, your activity level, and your overall well-being.
How to Use the BMI Calculator
- Enter your weight in kilograms.
- Enter your height in centimeters.
- Click “Calculate BMI.”
- The calculator will show you your individual BMI value and the corresponding category.
Our BMI calculator helps you get a better sense of your current body weight and track changes over time.
A simple starting point for your health journey
BMI gives you a quick overview and can be a good starting point for defining your personal health goals. However, it is not a substitute for individual consultation with a healthcare professional.
If you want to improve your weight or specifically boost your fitness, we’re happy to support you—with professional guidance, personalized training plans, and a holistic approach to greater well-being.
Editorial team at fitnessmarkt.de
Image source: #299191299 Frank H. / stock.adobe.com
Published on: 24 November 2025