Calculate Your BMI Online

Body mass index (BMI) is weight divided by height squared, and the World Health Organization uses it to categorize adult weight. The formula is simple: kilograms over meters squared. Below 18.5 counts as underweight, 18.5 to 25 as normal, 25 to 30 as overweight and above 30 as obese. This tool shows the number, its category and a color-coded bar, updating as you change the inputs. Keep in mind that BMI is a rough population measure: it ignores muscle mass, age and body build, is misleading for athletes, and does not apply during pregnancy or to children.

This tool runs entirely in your browser. No data is sent to any server.

How to use it

1. 1

   Type your weight in kilograms into the first box.

2. 2

   Enter your height in centimeters (not meters).

3. 3

   Read the BMI number and its category; the bar below shows where you sit on the scale.

Frequently asked questions

What is the normal BMI range?

For adults, 18.5 to 24.9 is considered normal. Below 18.5 is underweight, 25 to 29.9 overweight and 30 or above obese.

Is BMI accurate for athletes?

No. Muscle is denser than fat, so a lean athlete can still score a high BMI. A fuller picture comes from body-fat percentage and waist measurement too.

Is this a medical diagnosis?

No, it is only a rough statistical measure. Talk to a doctor or dietitian before making decisions about your diet or health.