Calculators · Free Tool
BMI Calculator
Calculate Body Mass Index from height and weight in metric or imperial units, with WHO category.
About this tool
Enter your height and weight, in metric (cm/kg) or imperial (ft-in/lb), and get your Body Mass Index with its WHO classification: underweight (below 18.5), normal (18.5–24.9), overweight (25–29.9), or obese (30+).
BMI is a quick population-level screening number, not a diagnosis: it does not distinguish muscle from fat and reads differently for athletes, older adults, and different body types. Treat it as one signal among many.
Common uses
- Get a quick baseline health indicator from height and weight
- Track how BMI shifts over a training or nutrition program
- Convert between metric and imperial BMI inputs effortlessly
Frequently asked questions
What is the BMI formula?
Weight in kilograms divided by height in meters squared (kg/m²). In imperial units it is weight in pounds × 703 ÷ height in inches squared.
Is BMI accurate for athletes?
Often not. Muscle weighs more than fat, so muscular people can read "overweight" while being lean. Waist measurement and body-fat percentage are better complements for athletic builds.
Is my data uploaded to a server?
No. This tool runs entirely in your browser using JavaScript, so nothing you type is transmitted, logged, or stored anywhere. You can even use it offline once the page has loaded.