BMI Calculator

Q: What does BMI stand for?

BMI stands for Body Mass Index.

Q: How is BMI calculated?

BMI is calculated from height and weight. The metric formula is weight in kilograms divided by height in metres squared. The imperial formula is 703 times weight in pounds divided by height in inches squared.

Q: What BMI is considered a healthy weight for adults?

For most adults, a BMI from 18.5 to below 25 is classified as the healthy-weight range.

Q: Does BMI measure body fat directly?

No. BMI uses height and weight and does not directly measure body fat or body composition.

Q: Can children use adult BMI categories?

No. BMI interpretation for children and teenagers depends on age and sex and requires age-specific assessment.

Q: Is BMI a medical diagnosis?

No. BMI is a screening measurement and not a medical diagnosis.

Calculate your Body Mass Index (BMI) using your height and weight. Choose metric or imperial units and get your BMI result instantly.

Weight (kg)

Height (cm)

Weight (lb)

Height (ft / in)

Your BMI is

Underweight
<18.5

Healthy Weight
18.5 - 24.9

Overweight
25 - 29.9

Obesity
30+

What Is BMI?

Body Mass Index (BMI) is a simple screening measure that compares an adult's weight with their height. It is commonly used to group BMI values into weight-status categories.

BMI can be useful as a general screening tool, but it does not directly measure body fat and cannot by itself determine a person's health. Factors such as age, muscle mass, body composition, and individual medical circumstances can affect how a BMI result should be interpreted.

How to Use This BMI Calculator

Using this free online BMI calculator is simple. Select your preferred measurement system first. For metric measurements, enter your weight in kilograms and your height in centimeters. For imperial measurements, enter your weight in pounds and your height in feet and inches. Then select Calculate My BMI to see your result.

How Is BMI Calculated?

BMI is calculated by comparing a person's weight with the square of their height. The formula depends on whether metric or imperial measurements are being used.

Metric BMI Formula

BMI = weight (kg) / height squared (m²)

For example, a person who weighs 70 kg and is 1.75 meters tall has a BMI of approximately 22.9.

Imperial BMI Formula

BMI = 703 × weight (lb) / height squared (in²)

Adult BMI Categories

BMI Range	Weight Status
Below 18.5	Underweight
18.5 - 24.9	Healthy Weight
25.0 - 29.9	Overweight
30.0 or above	Obesity

What Is a Healthy BMI Range?

For most adults, a BMI from 18.5 to below 25 is classified as the healthy-weight range. BMI is a screening measurement and should be considered together with other relevant health information rather than being treated as a medical diagnosis.

Why Can BMI Be Useful?

BMI provides a quick way to compare body weight with height. Because the calculation only requires height and weight, it is widely used as a simple screening measurement for adults.

However, BMI does not distinguish between muscle, fat, and other body tissues. People with different body compositions can therefore have similar BMI values.

Frequently Asked Questions About BMI

What does BMI stand for? BMI stands for Body Mass Index.

How is BMI calculated? BMI is calculated using a person's height and weight. This calculator automatically applies the appropriate formula depending on whether metric or imperial measurements are selected.

What BMI is considered a healthy weight for adults? For most adults, a BMI from 18.5 to below 25 is classified as the healthy-weight range.

Does BMI measure body fat directly? No. BMI uses height and weight and does not directly measure body fat or body composition.

Can children use these adult BMI categories? No. BMI interpretation for children and teenagers depends on age and sex and requires age-specific assessment. The adult BMI categories shown by this calculator should not be used for children.

Is BMI a medical diagnosis? No. BMI is a screening measurement rather than a medical diagnosis. A healthcare professional can consider BMI together with other health information when appropriate.

Important: This BMI calculator is intended for general educational and informational purposes for adults. It is not a medical diagnosis and does not replace professional medical advice. BMI may not accurately reflect body composition for every individual. Children and teenagers require age- and sex-specific BMI assessment.