BMI Calculator — body mass index
Calculate your Body Mass Index from height and weight (metric or imperial) and see your category — in your browser.
🔒 Runs entirely in your browser. Your input and output are never sent to a server or stored — fully private.
Enter your height and weight to get your Body Mass Index (BMI) and weight category.
BMI is a general screening tool and does not account for muscle, bone or fat distribution.
Estimates only — not medical advice.
About this tool
Enter your height and weight in metric or imperial units and this BMI calculator returns your Body Mass Index along with the category it falls into — underweight, normal, overweight or obese. It also shows the healthy weight range for your height, so you can see how far any goal might be. It is a quick way for adults to gauge whether their weight sits in a typical range. Every figure is worked out on your own device in the browser, so the height and weight you type are never uploaded anywhere.
Frequently asked questions
How is BMI calculated?
BMI is your weight in kilograms divided by the square of your height in metres, written as kg/m². For example, someone who is 1.75 m tall and weighs 70 kg has a BMI of 70 / (1.75 × 1.75), which is about 22.9. If you enter imperial units, the tool converts feet, inches and pounds to metric first, so the result is the same either way.
What do the BMI categories mean?
The usual adult bands 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 obese. These cut-offs come from population studies and are the same for men and women. They do not account for muscle, frame size, age or pregnancy, so a very muscular person can read as overweight despite carrying little fat.
Is BMI a reliable measure of health?
BMI is a rough screening figure, not a diagnosis. It says nothing about where fat sits or how much of your weight is muscle, so treat it as a starting point rather than a verdict. For any real decision about your weight or health, talk to a doctor or dietitian. The whole calculation runs locally in your browser, and nothing you enter is uploaded or stored.