What is BMI Calculator?
Body Mass Index (BMI) is a simple measure that uses your height and weight to estimate whether you are in a healthy weight range. A BMI calculator computes the number and places it into a category — underweight, normal, overweight or obese — giving a quick, widely used indicator of body composition.
This calculator supports both metric (kilograms and centimetres) and imperial (pounds and inches) units and shows the healthy reference range for context.
How to Use the BMI Calculator
- Choose metric or imperial units.
- Enter your weight and height.
- Click Calculate BMI.
- Read your BMI value and weight category with the healthy range shown.
Features of Our BMI Calculator
- Metric and imperial unit support
- Instant BMI value to one decimal place
- Clear weight-category classification
- Colour-coded result for quick reading
- Shows the healthy reference range
- Works offline and keeps your data private
Benefits & Use Cases
BMI is a fast starting point for anyone tracking fitness or health goals. It is used by individuals, coaches and clinics as an easy screening figure, though it should always be interpreted alongside other factors like muscle mass and body shape.
Since the calculation happens in your browser, your health data is never uploaded or stored anywhere.
The BMI Calculator is completely free, needs no sign-up or installation, and runs entirely in your browser — nothing you enter is uploaded to a server, so your data stays private. It works on desktop, tablet and mobile, in light or dark mode.
Tips & Best Practices
Enter height and weight in a single unit system — metric (kg, cm) or imperial (lb, in) — and the tool places your BMI into the standard categories with the healthy range shown for context. BMI is a quick screening figure, not a diagnosis: it does not distinguish muscle from fat, so athletes and some body types read higher than their health warrants.
Treat the result as general information rather than medical advice; see our disclaimer for details. To explore related numbers, the Percentage Calculator and Age Calculator are a click away.
FAQ about BMI Calculator
How is BMI calculated?
BMI equals weight in kilograms divided by height in metres squared. In imperial units it is 703 times weight in pounds divided by height in inches squared.
What is a healthy BMI?
A BMI between 18.5 and 24.9 is generally considered a healthy weight range for most adults.
Is BMI accurate for everyone?
BMI is a useful general guide but does not distinguish muscle from fat, so athletes and some body types may read higher. Treat it as one indicator, not a diagnosis.
Is my health data private?
Yes. Your weight and height are only used in your browser to calculate BMI and are never sent anywhere.