Body Mass Index is one of the quickest ways to gauge whether your weight sits in a healthy range for your height. In this guide we walk through the formula, a worked example, and the important caveats.

The formula

Metric: BMI = weight (kg) / height (m)². Imperial: BMI = 703 × weight (lb) / height (in)².

Worked example

A person weighing 70 kg at 1.75 m tall: 70 / (1.75 × 1.75) = 22.9, which falls in the normal range. You can confirm this with our BMI calculator.