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BMI Calculator

Calculate your Body Mass Index in metric or imperial units.

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Enter your height and weight. We compute BMI = weight (kg) / height (m)². BMI is a rough screening tool - not a diagnosis - and is less useful for very muscular people.

Your BMI

22.9

Normal weight

How to use it

  1. Pick your unit system

    Metric (kg, cm) or Imperial (lb, ft/in). Same formula either way.

  2. Enter height and weight

    The BMI updates as you type. Decimal precision is fine.

  3. Read the category

    The category band is shown alongside your BMI. Treat it as a screening prompt, not a diagnosis.

What is it?

Body Mass Index (BMI) is a single number derived from your weight and height: kg ÷ m². It's the most widely used screening tool to flag whether an adult's weight may be in a range associated with elevated health risks. The WHO categories - underweight, normal, overweight, obese - are population-level thresholds, useful as a starting signal but not a diagnosis.

When to use it

As a fast screening check during a routine self-assessment or before a doctor's visit. Useful for spotting trends over months or years. Insurance and corporate wellness programs often use BMI brackets to set premiums or eligibility. Combine with waist circumference for a more informative picture, especially around the borderline of categories.

Common mistakes

Treating BMI as a body-composition measurement - it isn't. Muscle weighs more than fat, so muscular athletes routinely score 'overweight' or 'obese' while having very low body-fat percentages. BMI also has known limitations for older adults (who lose muscle and gain fat at the same weight), pregnant people, very tall or very short people, and across ethnic groups where the threshold for elevated risk differs.

FAQ

What is a healthy BMI?
The WHO classifies BMI 18.5–24.9 as normal weight, 25–29.9 as overweight, and 30+ as obese. These thresholds are population-level guidelines, not individual diagnoses.
Is BMI accurate for athletes?
Often not. BMI doesn't distinguish muscle from fat, so muscular people can land in the 'overweight' range while being lean.

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