BMI Calculator
Calculate Body Mass Index in metric or imperial units, with a category result.
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About the BMI Calculator
Calculate your Body Mass Index (BMI) in seconds. Switch between metric (kilograms and centimeters) and imperial (pounds, feet, and inches) units. We show your BMI value along with the World Health Organization category so you can interpret the result at a glance.
How to use the BMI Calculator
- 1Choose your unit system: metric (kg + cm) or imperial (lb + ft + in).
- 2Enter your weight.
- 3Enter your height.
- 4Read your BMI value and category — Underweight, Normal, Overweight, or Obese.
Why use our BMI Calculator
Metric & imperial
Toggle freely between unit systems without losing your input.
WHO categories
Result is mapped to the standard WHO BMI bands.
Instant
BMI updates as you type.
Private
Your weight and height never leave the browser.
Frequently asked questions
How is BMI calculated?+
Metric: BMI = weight (kg) ÷ height (m)². Imperial: BMI = 703 × weight (lb) ÷ height (in)². Both formulas give the same number for the same person.
What are the BMI categories?+
WHO categories: Underweight below 18.5, Normal 18.5–24.9, Overweight 25–29.9, and Obese 30 and above.
Is BMI accurate for everyone?+
BMI is a general screening tool, not a diagnosis. It doesn't distinguish between muscle and fat, so very muscular people can score high and some healthy people may score low. For health decisions, consult a doctor.
Is my data stored?+
No. Everything is calculated locally and never uploaded.