BMI Calculator
Body mass index.
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About BMI Calculator
The BMI Calculator instantly finds your Body Mass Index from your height and weight. Switch between metric (centimeters and kilograms) and imperial (feet, inches, and pounds) units, and the result updates live as you type, showing your BMI to one decimal place along with its weight category.
It is completely free with no sign-up, and it runs entirely in your browser. Your height and weight are never sent to a server or stored anywhere, so your measurements stay private on your own device.
Frequently asked questions
- Is the BMI Calculator free to use?
- Yes, it is 100% free with no account, sign-up, or limits on how many times you can use it.
- Is my data uploaded or stored?
- No. All calculations happen locally in your browser, and your height and weight are never sent to a server or saved anywhere.
- How is BMI calculated?
- BMI is your weight in kilograms divided by the square of your height in meters. For imperial units we use 703 times your weight in pounds divided by your height in inches squared.
- What do the BMI categories mean?
- Under 18.5 is Underweight, 18.5 to 24.9 is Normal weight, 25 to 29.9 is Overweight, and 30 or above is Obese.
- Can I switch between metric and imperial units?
- Yes. Use the units dropdown to toggle between metric (cm and kg) and imperial (ft, in, and lb), and the BMI recalculates instantly.
- Is BMI an accurate measure of health?
- BMI is a useful general screening tool but does not account for muscle mass, body composition, age, or sex, so consult a healthcare professional for personalized advice.