BMI Calculator
Calculate Body Mass Index from height and weight, with the standard category.
How to use the BMI Calculator
Enter your values and pick a mode if the tool offers one.
Click calculate — results appear instantly, computed in your browser.
Copy the result or save the tool to your favorites.
Frequently asked questions
Weight in kilograms divided by height in metres squared (kg/m²).
Below 18.5 is underweight, 18.5–24.9 normal, 25–29.9 overweight, 30 and above obese.
It is a general screen. It does not distinguish muscle from fat, so athletes may read high. Treat it as a rough guide.
No. Discuss health decisions with a qualified professional rather than relying on BMI by itself.
No. Height and weight are used only in your browser.
About the BMI Calculator
Body Mass Index, or BMI, is a simple screening measure that relates your weight to your height. This calculator computes your BMI from height in centimetres and weight in kilograms, and places the result in the standard category used by health organisations worldwide.
How BMI is calculated
BMI is your weight in kilograms divided by the square of your height in metres. The standard categories are: below 18.5 is underweight, 18.5 to 24.9 is the normal range, 25 to 29.9 is overweight, and 30 or above is classified as obese. These thresholds are general guidelines used for population-level screening.
What BMI can and cannot tell you
BMI is a quick, useful first indicator, but it has real limitations. It does not distinguish muscle from fat, so very muscular people such as athletes can register as overweight despite low body fat. It also does not account for age, sex, bone density, or where fat is distributed on the body. For these reasons BMI is best treated as one rough signal among many, not a definitive measure of health.
Using your result wisely
If your BMI falls outside the normal range, that is a prompt to consider your overall health rather than a diagnosis. Many factors influence wellbeing that BMI cannot capture. Any decisions about diet, exercise, or weight should be made with a qualified healthcare professional who can consider your full circumstances.
Privacy
Your height and weight are used only in your browser to compute the result and are never sent anywhere or stored. For related calculations, the Calorie Calculator estimates daily energy needs, and the Age Calculator works out exact age. This tool is for general information and is not a substitute for medical advice.