BMI Calculator

About This Tool

This body mass index calculator estimates BMI by comparing your weight with your height. You can choose metric or US units, enter your measurements, and receive a numerical result with the matching general adult category.

The result is intended for adults aged 20 and older. It can support general health awareness, but it should not be treated as a diagnosis, a direct body-fat measurement, or a complete assessment of your health.

How to Use the Tool

1. Select metric or US units.
2. Enter your height in centimeters, or feet and inches.
3. Enter your weight in kilograms or pounds.
4. Enter your age and select your sex.
5. Click the calculate button.
6. Review the BMI value and general adult category.
7. Read the limitations below before interpreting the result.

The body mass index calculator uses the same height-to-weight relationship for adults regardless of sex, so the number itself does not change between male and female. Age does change how the number is read: from age 20 the general adult categories apply, while for ages 2 to 19 the tool shows the BMI value but withholds the adult category, because those ranges are not the correct comparison. Always check that your height and weight use the selected unit system before calculating.

What Is BMI?

Body mass index is a screening value based on a person’s weight relative to height. It offers a quick way to group adult results into general categories such as underweight, healthy weight, overweight, and obesity.

BMI does not directly measure body fat, muscle mass, bone density, or fat distribution. Two people with the same result may still have different body composition and health needs.

How to Calculate BMI

The BMI formula depends on the unit system used.

Metric Units

BMI = Weight in kilograms ÷ Height in meters²

Example: a weight of 70 kg and a height of 1.75 m gives 70 ÷ 1.75², which is approximately 22.9.

US Units

BMI = Weight in pounds × 703 ÷ Height in inches²

The calculator applies the correct equation automatically after you select the unit system, so both give the same BMI for the same body.

Adult BMI Categories

These ranges are general screening categories for adults. They do not explain why a person falls into a category or determine an individual treatment plan.

What Does the Result Mean?

Your result shows how your entered weight relates to your height. A category can provide a useful starting point for a broader health discussion, but it should be interpreted with other information.

Factors such as muscle mass, age, medical history, waist measurement, activity level, pregnancy, physical examination findings, and laboratory results may provide important context.

Limitations of BMI

BMI has several limitations:

• It does not directly measure body fat.
• It cannot distinguish fat from muscle.
• Muscular adults may receive a higher result without having excess body fat.
• Older adults may have reduced muscle mass that the result does not show.
• It does not show where body fat is stored.
• It does not account for every individual or population difference.
• It should not be the only basis for medical, diet, or exercise decisions.

Use the result as a general screening estimate rather than a final judgment about health.

BMI for Men and Women

People sometimes search for BMI calculator men, BMI calculator male, BMI calculator women, or BMI calculator female. For adults, the standard equation uses height and weight in the same way.

Sex can still matter when a healthcare professional evaluates body composition, health risks, hormones, pregnancy, or other personal factors. The numerical calculation itself does not use a separate standard adult equation for men and women.

BMI for Children and Teenagers

Adult categories should not be used for children or teenagers. For ages 2 through 19, BMI is interpreted with age- and sex-specific percentiles.

Use a properly designed child and teen tool or speak with a qualified healthcare professional instead of applying adult ranges to younger users.

When to Speak With a Healthcare Professional

Consider discussing the result with a qualified professional when:

• You are concerned about an unexpected result.
• Your weight changes quickly or without a clear reason.
• You are pregnant.
• You are an athlete with substantial muscle mass.
• You have a medical condition that affects weight or body composition.
• You are considering major diet, medication, or exercise changes.
• You are evaluating a child or teenager.

Medical Disclaimer

This BMI calculator is provided for general informational and educational purposes only. The results are estimates based on the height and weight you enter and should not be treated as a diagnosis, medical assessment, or final evaluation of your health. BMI does not directly measure body fat or account for factors such as muscle mass, age, pregnancy, medical history, or body composition. Always consult a qualified doctor or healthcare professional before making decisions about your weight, diet, exercise, medication, or overall health.

Start Calculating

Enter your measurements above and use the body mass index calculator to calculate BMI from your height and weight. Review the result as a general screening estimate, not a diagnosis.