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 — 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 — nothing you type is transmitted, logged, or stored anywhere. You can even use it offline once the page has loaded.