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BMI Calculator

Body Mass Index in seconds

Enter your height and weight to find your Body Mass Index (BMI) and see which weight category you fall into.

Height (cm)
Weight (kg)
Your BMI
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About the bmi calculator

Body Mass Index (BMI) is a widely used screening measure that relates your weight to your height. It gives a quick single number that places you in a weight category — underweight, normal weight, overweight, or obese — and is commonly used by doctors and fitness professionals as a starting point for assessing healthy weight.

This calculator supports both metric (centimetres and kilograms) and imperial (feet, inches and pounds) units. The result updates instantly as you type, so you can experiment with different values without pressing a button.

The formula

  • Metric: BMI = weight (kg) ÷ height (m)²
  • Imperial: BMI = 703 × weight (lb) ÷ height (in)²

BMI is a guide, not a diagnosis — it does not distinguish muscle from fat, so very athletic people may read high. Always consult a healthcare professional for personal advice.

How to use the bmi calculator

  1. Choose your units

    Switch between metric (cm, kg) and imperial (ft, in, lb).

  2. Enter your height and weight

    Type your measurements — your BMI appears instantly.

  3. Read your category

    The result shows your BMI number and weight category.

Frequently asked questions

What is a healthy BMI range?
For most adults, a BMI between 18.5 and 24.9 is considered a normal, healthy weight. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is obese.
Is BMI accurate for athletes?
BMI does not separate muscle from fat, so very muscular people can register as overweight or obese despite low body fat. Treat it as a rough guide rather than a precise measure of health.
Does BMI apply to children?
The adult BMI categories do not apply directly to children and teens, whose BMI is plotted on age- and sex-specific growth charts. This tool is intended for adults.
Is the BMI calculator free?
Yes, it is completely free and requires no sign-up. All calculation happens in your browser.

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