BMI Calculator
Free BMI calculator. Enter your height and weight in metric or imperial units to instantly get your Body Mass Index and weight category (underweight, normal, overweight, obese).
Body Mass Index (BMI) is a quick screening number that relates your weight to your height. It is calculated as weight in kilograms divided by height in metres squared, and it places most adults into one of four broad categories: underweight, normal weight, overweight, or obese. This calculator works in both metric and imperial units and updates live as you type.
BMI is a useful general indicator, but it does not distinguish muscle from fat and does not account for age, sex, or body composition. Results are estimates for informational purposes only and are not medical advice — talk to a healthcare professional about what your numbers mean for you.
Frequently asked questions
How is BMI calculated?
BMI equals your weight in kilograms divided by the square of your height in metres (kg/m²). Imperial inputs are converted to metric before the calculation.
What are the BMI categories?
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 athletes?
Not always. BMI cannot tell muscle from fat, so very muscular people may register as overweight despite low body fat. Treat it as a rough screening tool, not a diagnosis.
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