BMI Calculator
Enter your height and weight to calculate your Body Mass Index.
What is BMI?
Body Mass Index (BMI) is a simple measure that estimates whether your weight is healthy for your height. It's calculated from just two numbers — height and weight — and is widely used by doctors and health organizations as a quick screening tool, though it doesn't account for muscle mass, bone density, or body composition directly. For more on where BMI comes from and its limitations, see our full guide to BMI.
BMI formula
BMI = weight (kg) ÷ height (m)²
For example, someone who is 170 cm (1.7 m) tall and weighs 65 kg has a BMI of 65 ÷ (1.7 × 1.7) = 22.5, which falls in the "normal weight" range.
BMI categories
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Normal weight |
| 25.0 – 29.9 | Overweight |
| 30.0 and above | Obese |
Frequently asked questions
Is BMI accurate for everyone?
BMI is a useful general screening tool, but it doesn't distinguish between muscle and fat. Athletes with high muscle mass may show a higher BMI without excess body fat, and it may be less accurate for older adults, children, or pregnant women.
What is a healthy BMI range?
For most adults, a BMI between 18.5 and 24.9 is considered a healthy weight range. Values outside this range don't automatically indicate a health problem, but they can be a signal to talk to a doctor.
Does BMI differ by sex or age?
The standard BMI formula and categories are the same for adult men and women. They aren't designed for children or teens, who are assessed using age- and sex-specific growth charts instead.