BMI Calculator
BMI Calculator works out your Body Mass Index from your height and weight, and shows the healthy weight range for that height, free and in your browser. You enter height and weight, and the result updates straight away.
Last updated: 30 October 2026 · Free · No signup
Body Mass Index, or BMI, is a simple ratio: weight divided by height squared. It is used as a rough screening measure, not as a complete health assessment, because it does not distinguish muscle from fat, and it does not account for age, sex, or body shape. The healthy weight range shown here is the range of weights that would give a BMI in the commonly used healthy band for that height, which is a useful starting point for a conversation, not a diagnosis.
Use height and weight measured recently, and in the same units the tool expects, because mixing centimetres with inches or kilograms with pounds will give a wrong result. If the result surprises you, check the inputs first, and remember that BMI alone does not tell the whole story about health.
Privacy: this tool runs entirely in your browser — no upload, no signup, and your files never leave your device.
Work out your Body Mass Index (BMI) from your height and weight — and see the healthy weight range for your height too.
How to use BMI Calculator
- Enter your height.
- Enter your weight.
- Read your BMI and the healthy weight range.
- Use the result as a starting point, not a diagnosis.
Key facts
| Formula | BMI = weight in kilograms divided by height in metres squared |
|---|---|
| Result | Your BMI, plus the healthy weight range for your height |
| Note | A screening measure, not a medical diagnosis |
Frequently asked questions
What is a healthy BMI?
A BMI between 18.5 and 24.9 is commonly described as the healthy range for adults. Below that is described as underweight, and above it as overweight or obese in broad bands, but these bands are screening guides, not diagnoses for any individual.
Does BMI work for athletes or muscular people?
Not always well. Muscle weighs more than fat, so a very muscular person can have a high BMI without having excess body fat. BMI is a rough population measure, and for an individual it should be considered alongside other measures, such as waist size and overall fitness.
How do I calculate BMI by hand?
Divide your weight in kilograms by your height in metres, squared. For example, a person who weighs 70 kilograms and is 1.75 metres tall has a BMI of 70 divided by 1.75 squared, which is about 22.9.
Is my height and weight uploaded or saved?
No. The calculation happens in your browser only. Nothing is sent to a server and nothing is saved after you close the page.