BMI Calculator
BMI is a rough indicator and not medical advice.
How it works
Choose metric or imperial units, enter your weight and height, and the tool returns your Body Mass Index along with the WHO category it falls into: underweight, normal, overweight, or obese. The result updates as you adjust the inputs, so you can see how a different weight or height changes the figure.
BMI is weight in kilograms divided by height in metres squared. The imperial form is 703 times pounds divided by inches squared, which produces the same number from lb and in. It is a widely used screening figure, useful as a rough self-check or as the starting point for a conversation with a doctor, but it is not a diagnosis: it does not account for muscle mass, bone density, age, or body composition, so very muscular or very lean people can read high or low.
All calculation happens locally, so your height and weight are processed inside the browser tab and never transmitted anywhere.
Frequently Asked Questions
How is BMI calculated?
- BMI = weight (kg) / height (m)². In imperial units the formula is BMI = 703 × weight (lb) / height (in)².
Is BMI a reliable health indicator?
- Only as a rough screening tool. It does not account for muscle mass, bone density, or body composition, and it is not a medical diagnosis. Treat it as a starting point rather than a conclusion.
Is my data safe?
- Yes. The tool is a static client-side app with no backend, so your input is processed by JavaScript running inside your browser tab and is never transmitted anywhere. You can confirm it by opening DevTools → Network: using the tool produces zero outbound HTTP requests.