BMI Calculator

Calculate your Body Mass Index for free, with healthy weight range, BMI Prime, and Ponderal Index. Adults 20 and older.

Units
ft
in
Your BMI
22.5kg/m²
Normal

BMI between 18.5 and 24.9 is generally associated with the lowest risk of weight-related health conditions.

BMI is a screening measure, not a diagnosis. Results are educational and do not replace a clinician’s assessment.

How BMI is calculated

Body Mass Index (BMI) is a screening tool that estimates body fat based on your height and weight. It is commonly used to classify weight categories such as underweight, normal weight, overweight, and obesity in adults.

BMI is calculated by dividing your weight by your height squared. While BMI does not directly measure body fat, it can help identify potential health risks associated with higher or lower body weight.

This BMI calculator helps estimate your BMI score and weight category using standard medical BMI ranges for adults.

Related health and weight guides

BMI ranges are generally categorized as underweight, normal weight, overweight, and obesity. However, BMI may not fully account for factors like muscle mass, body composition, age, or athletic training.

Maintaining a healthy weight through balanced nutrition, regular physical activity, sleep, and stress management can support long-term health and reduce the risk of conditions like heart disease, diabetes, and high blood pressure.

Looking for nutrition support? Explore our nutrition and healthy eating guides for practical tips on meal planning, healthy habits, and sustainable weight management.

Questions about BMI, healthy weight, or nutrition?

august is a private AI health companion that can help explain BMI ranges, weight management, nutrition, exercise, healthy habits, and wellness goals without a clinic visit or copay.

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Frequently Asked Questions

For most adults a BMI between 18.5 and 24.9 is considered the healthy range. It is a guide for population-level risk, not a strict target for every individual.

BMI is your weight in kilograms divided by your height in metres squared. The calculator handles the conversion automatically whether you enter metric or US units.

Not always. BMI cannot separate muscle from fat, so very muscular people can read as overweight even with low body fat. Pair it with other measures like waist size or body composition.

Childhood and teen BMI is read against age and sex growth percentiles, not the adult categories. For anyone under 20, treat this result as a rough guide and check with a clinician.

BMI Prime is your BMI divided by 25, the upper limit of the healthy range. A value below 1 sits inside the healthy range, and a value above 1 shows how far you are over it.

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