Free BMI Calculator - Calculate Your Body Mass Index & Health Category
Calculate your Body Mass Index using metric or imperial units. Understand weight categories and health classification.
Formula & Methodology
This calculator divides your weight by the square of your height to calculate your Body Mass Index, then classifies the result into standard categories such as underweight, normal, overweight, or obese.
- BMI = weight (kg) / height (m)²
- BMI = 703 × weight (lbs) / height (in)²
Worked Example
Using the BMI Calculator: apply the formula above to your input values. For instance, BMI = weight (kg) / height (m)², then BMI = 703 × weight (lbs) / height (in)². The tool performs each step instantly and shows the result.
Frequently Asked Questions
What is a healthy BMI range?
For most adults, 18.5 to 24.9 is considered the healthy range, with below 18.5 underweight and 25 or above overweight.
Is BMI accurate for athletes?
Not always. BMI does not distinguish muscle from fat, so very muscular people can read as "overweight" despite low body fat.
How is BMI calculated?
It divides your weight in kilograms by your height in metres squared (or uses the imperial equivalent with a conversion factor).