Adult BMI calculator

Our BMI calculator works for women and men. Complete the form below and select the BMI only option to calculate your BMI number.

To create your personalized body mass index (BMI) health report, select the BMI health report option. Your personalized report includes your BMI number, BMI classification, and optionally waist to hip ratio and suggested daily caloric intake.

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What is BMI?

Body mass index (BMI) is a tool used to estimate the amount of body fat a person has based on their weight and height. It's calculated by dividing a person's weight in kilograms by the square of their height in meters.

Ways that BMI is used

Body mass index, or BMI, is a tool used to measure body fat based on a person's height and weight. It's used in various settings for different purposes:

Healthcare
Doctors and nurses often calculate BMI during check-ups to assess if a person is underweight, normal weight, overweight, or obese. This helps them give advice on how to maintain or reach a healthy weight.
Nutrition and Dietetics
Nutritionists use BMI to create personalized diet plans. Understanding someone's BMI can guide them in recommending more or less of certain foods to help reach a healthier weight.
Fitness Industry
Personal trainers might calculate a client's BMI to tailor fitness programs that aim for weight loss, muscle gain, or maintaining a healthy lifestyle.
Insurance
Some insurance companies use BMI as part of their criteria to determine policy rates. Higher BMIs might lead to higher premiums due to associated health risks.
Research and Public Health
Researchers use BMI to study obesity rates and health patterns across different populations. This can inform public health policies and programs aimed at reducing obesity and improving overall health.
Schools
In some regions, schools measure students' BMI to monitor the general health of the student population and to identify trends in childhood obesity.
Workplace Wellness Programs
Employers might include BMI calculations in their wellness programs to encourage employees to maintain or achieve a healthy weight, often providing resources or incentives to do so.

BMI is used whenever there's a need to quickly estimate a person's body fat as part of assessing their overall health or to tailor health, nutrition, or fitness advice. It's a widely used measure because it's easy to calculate and requires only two pieces of information: height and weight.

Limitations of BMI

While BMI is a quick and easy tool for estimating body fat, it has several limitations. Firstly, BMI does not measure body fat directly. It also doesn't account for factors like sex, ethnicity, muscle mass, or age. For example, athletes may have a high BMI due to increased muscle mass, not body fat. Similarly, elderly people may have a higher BMI due to loss of muscle mass. Therefore, while BMI can be a useful tool, it should not be the sole indicator of a person's health.

Alternatives to BMI

There are several alternatives to BMI available, including the following:

  • Body fat percentage: This measures how much of your body is made up of fat, rather than just weight or height. Methods to measure this include skinfold measurements, bioelectrical impedance, and DEXA scans.
  • Waist-to-hip ratio: This looks at the circumference of your waist compared to your hips. It helps show how fat is distributed in your body, which can affect your health risks.
  • Waist-to-height ratio: By dividing your waist size by your height, this ratio can give a good sense of whether you have too much belly fat, which is linked to higher health risks.
  • Body shape index: This newer method uses your waist circumference, weight, and height to predict health risks better than BMI alone.

How BMI is calculated

In the metric system the formula is: BMI = weight (kg) / height (m^2)

In the imperial system the formula is: BMI = (weight (lbs) / height (in^2)) x 703

How to solve the BMI equation

Follow these steps to calculate BMI for inches and pounds. (If you are using the metric system, skip step 3.) If you don't know your height in inches, you can find it by multiplying how tall you are in feet by 12. So if you are 5 feet 3 inches tall, your height is 5 × 12 = 60 plus 3 inches, or 63 inches tall.

  1. Square your height: Multiply your height in inches by itself. For example, if you are 68 inches tall, it would be 68 × 68.
  2. Divide your weight by your squared height: Take your weight in pounds and divide it by the result from step 1. If you weigh 150 lbs, and using the height example above, it would be 150 ÷ ( 68 × 68 ).
  3. Multiply by 703: Take the result from step 2 and multiply it by 703. Continuing the example, if the result from step 2 is 0.3235, it would be 0.3235 × 703.

The final result is your BMI. This equation adjusts the BMI formula to use pounds and inches instead of kilograms and meters, making it suitable for common measurements used in the United States.

Health advice

The information that we offer is no substitute for discussing any health questions or concerns that you might have with your health care provider. We recommend talking to your health care provider about any changes that you're considering to your diet or exercise plan, particularly if you have any known medical conditions.