BMI Calculator
Find your Body Mass Index in metric or imperial units.
Your BMI appears here
Choose your units and enter your height and weight. Your Body Mass Index and its category update live — computed in your browser, with nothing sent to a server.
Runs entirely in your browserCalculate your BMI, locally
Body Mass Index estimates how your weight compares to your height. Pick metric (centimetres and kilograms) or imperial (feet, inches, and pounds), enter your measurements, and the BMI and its category appear as you type. BMI is a rough screening number, not a diagnosis — it does not account for muscle, build, or body composition. Everything is computed in your browser and nothing is uploaded.
Common questions
How is BMI calculated?
BMI is your weight in kilograms divided by your height in metres squared (kg ÷ m²). This tool converts imperial measurements to metric first, then applies the same formula, so both unit systems give the same result.
What do the BMI categories mean?
Using the standard World Health Organization ranges: below 18.5 is underweight, 18.5 to 24.9 is normal weight, 25 to 29.9 is overweight, and 30 or above is obese.
Is BMI accurate for everyone?
BMI is a general screening tool, not a medical diagnosis. It does not distinguish muscle from fat, so very muscular people can read as overweight, and it is less reliable for children, athletes, and older adults. Treat it as a rough guide.
Can I switch between metric and imperial?
Yes. Use the unit toggle at the top. In metric you enter centimetres and kilograms; in imperial you enter feet plus inches and pounds. The BMI is identical either way.
Are my measurements uploaded?
No. The calculation runs entirely in your browser with JavaScript. Your height and weight are never sent to a server or stored anywhere.