Health & Fitness
BMI Calculator
Check your Body Mass Index in metric or imperial units — instantly and free.
BMI Calculator
What is BMI?
Body Mass Index (BMI) is a simple number that relates your weight to your height. It is a rough screening tool used to flag whether an adult is underweight, at a healthy weight, overweight or obese.
BMI categories for adults
| BMI range | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Normal weight |
| 25.0 – 29.9 | Overweight |
| 30.0 and above | Obese |
BMI does not distinguish muscle from fat and is not a diagnosis. Athletes and children need different measures — consult a professional.
Frequently asked questions
What is a healthy BMI?
For most adults a BMI between 18.5 and 24.9 is considered healthy. Below 18.5 is underweight and 25 or above is overweight.
How is BMI calculated?
BMI = weight in kilograms divided by height in metres squared. In imperial units it is weight in pounds × 703 divided by height in inches squared.
Is BMI accurate for everyone?
No. It can misclassify very muscular people as overweight and does not account for age, sex or body composition. Treat it as a rough guide, not a diagnosis.
Does BMI differ for men and women?
The BMI formula is the same, but the healthy range is interpreted slightly differently by age and sex. This calculator shows the standard adult categories.