BMI Calculator
Enter your height and weight to instantly see your Body Mass Index and weight category — fast, free and completely private.
Body Mass Index is the standard screening measure doctors use to judge whether an adult's weight is healthy for their height. This free BMI calculator divides your weight in kilograms by the square of your height in metres, then places your result into one of four colour-coded categories so you can understand it at a glance.
Enter your height in centimetres and weight in kilograms, then press Calculate BMI.
How to use the BMI Calculator
- Type your height in centimetres and your weight in kilograms into the two boxes above.
- Click the Calculate BMI button to see your index and your colour-coded weight category instantly.
- Use Clear to reset the fields, and repeat any time — for example, to track your progress month by month.
BMI Calculator — FAQs
Is this BMI calculator free to use?
Yes, it is completely free with no signup, no limits and no hidden charges. You can calculate your BMI as many times as you like, and every calculation happens privately inside your own browser, so your health data is never sent anywhere or stored.
What is a healthy BMI range?
The World Health Organization defines a healthy BMI for adults as 18.5 to 24.9. Below 18.5 is classed as underweight, 25 to 29.9 as overweight, and 30 or above as obese. These cut-offs apply to adult men and women of all ages.
Is my health data uploaded or stored anywhere?
No. This calculator runs entirely in your web browser using JavaScript on your device. Nothing you type is uploaded to a server, saved in a database or shared with anyone, so your height and weight remain completely private.
How accurate is BMI as a health measure?
BMI is a useful screening guide but not a full health diagnosis, because it cannot tell muscle apart from fat. Very muscular people, athletes and pregnant women can get misleading results. Use it as a starting point and talk to a doctor for personal medical advice.