BMI Calculator

Body Mass Index (BMI) is the most widely used quick screen for whether a person's weight is in a healthy range for their height. It is used by doctors, gyms, insurers, and health apps worldwide because it needs only two numbers and gives an instantly comparable result.

The formula

BMI is your weight in kilograms divided by the square of your height in metres: BMI = kg ÷ m². In imperial units it is 703 × pounds ÷ inches². This calculator supports both, so you can enter whichever units you have.

What the number means

The World Health Organization classifies adult BMI into four bands:

- **Under 18.5** — underweight - **18.5 to 24.9** — normal (healthy) weight - **25.0 to 29.9** — overweight - **30.0 and above** — obese

The tool also shows the healthy weight range for your exact height, so you can see the target rather than just the label.

The limitations you should know

BMI is a screening tool, not a diagnosis, and it has real blind spots. It cannot tell muscle from fat, so a muscular athlete can score as "overweight" while carrying very little fat. It does not account for where fat is stored (belly fat carries more risk), and it is interpreted differently for children, older adults, pregnant people, and some ethnic groups. Use BMI as a starting point and talk to a health professional for a real assessment.

Privacy

Your height and weight never leave your browser — the calculation is done entirely on your device.