BMI Calculator
BMI (Body Mass Index) is a quick way to see whether your weight sits in a healthy range for your height. Enter your height and weight in metric or US units and this calculator gives you your BMI and the category it falls into.
Enter values above to see the result.
How it works
BMI compares your weight to your height using one simple formula:
BMI = weight (kg) ÷ height (m)²
If you work in pounds and inches, the calculator converts them to kilograms and metres first (1 lb = 0.45359237 kg, 1 inch = 0.0254 m), so you get the same answer whichever units you pick.
The categories
The standard adult categories from the World Health Organization are:
- Under 18.5 — Underweight
- 18.5 to 24.9 — Normal weight
- 25 to 29.9 — Overweight
- 30 and above — Obese
A worked example
Someone who is 1.75 m tall and weighs 70 kg:
70 ÷ (1.75 × 1.75) = 22.9
A BMI of 22.9 sits in the normal, healthy range.
What BMI doesn't tell you
BMI looks only at height and weight — it can't tell muscle from fat or show where weight is carried. An athlete with a lot of muscle can land in the "overweight" band while being perfectly healthy, and BMI isn't the right tool for children or during pregnancy. Use it as a rough check, and talk to a doctor for anything that matters.
Frequently asked questions
What is a healthy BMI?
For most adults, a BMI between 18.5 and 24.9 is considered the normal, healthy range. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or above is in the obese range.
How is BMI calculated?
BMI is your weight in kilograms divided by the square of your height in metres (kg/m²). If you enter US units, the calculator converts pounds and inches to metric first, so the result is the same either way.
Is BMI accurate for everyone?
BMI is a useful general guide, but it doesn't measure body fat directly. Very muscular people can read as overweight, and it isn't designed for children, pregnant people, or the very elderly. Treat it as a starting point, not a diagnosis.