BMI Calculator

What is BMI?

The BMI calculator finds the body mass index given the weight and the height. Enter the height in feet and inches or in cm or meters. Enter the weight in pounds or kg. The BMI is calculated by dividing an adult's weight in kilograms by their height in meters squared. The result is then compared to the following weight categories to see where the individual falls:

Underweight BMI ends up being below 18.5

Normal BMI ranges from 18.5 to 24.9

Overweight BMI ranges from 25.0 to 29.9

Obese BMI is 30.0 and above

The BMI is meant to be used as a simple means of classifying average sedentary (physically inactive) populations, with an average body composition. For such individuals, the current value recommendations are as follow: a BMI from 18.5 up to 25 may indicate optimal weight, a BMI lower than 18.5 suggests the person is underweight, a number from 25 up to 30 may indicate the person is overweight, and a number from 30 upwards suggests the person is obese.

BMI Categories:

BMI Range	Category
Below 18.5	Underweight
18.5 - 24.9	Normal weight
25.0 - 29.9	Overweight
30.0 and above	Obese

BMI Limitations

Although BMI is a widely used and useful indicator of healthy body weight, it does have its limitations. BMI is only an estimate that cannot take body composition into account. Due to a wide variety of body types as well as distribution of muscle, bone mass, and fat, BMI should be considered along with other measurements rather than being used as the sole method for determining a person's healthy body weight.

In adults:

• BMI cannot differentiate between muscle and fat. A person with large muscle mass may have a BMI in the overweight range, but still be healthy.
• BMI may not be accurate for elderly individuals who have lost muscle mass.
• BMI may not be accurate for individuals with eating disorders.

Children and BMI

The CDC and AAP both recommend the use of BMI to screen for overweight and obesity in children and adolescents aged 2 through 19 years. For children and adolescents, BMI is age and sex-specific and is often referred to as BMI-for-age. In children, a high amount of body fat can lead to weight-related diseases and other health issues and being underweight can also put one at risk for health issues.

The CDC growth charts take into account these differences and allow translation of a BMI into a percentile for a child's sex and age. A BMI between the 85th and 95th percentile indicates that the child is overweight. A BMI above the 95th percentile indicates that the child is obese.

How to Calculate BMI

BMI is a person's weight in kilograms divided by the square of height in meters. BMI does not measure body fat directly, but research has shown that BMI correlates to direct measures of body fat, such as underwater weighing and dual energy x-ray absorptiometry (DXA).

Formula & Calculation

Metric Formula:

BMI = weight (kg) / [height (m)]²

Imperial Formula:

BMI = (weight (lb) / [height (in)]²) × 703

Example Calculations:

Metric Example:
Weight = 68 kg, Height = 165 cm (1.65 m)
Calculation: 68 ÷ (1.65)² = 24.98

Imperial Example:
Weight = 150 lbs, Height = 5'5" (65 inches)
Calculation: [150 ÷ (65)²] × 703 = 24.96

Healthy Weight Range

Maintaining a healthy weight is important for overall health and can help you prevent and control many diseases and conditions. If you are overweight or obese, you are at higher risk of developing serious health problems, including heart disease, high blood pressure, type 2 diabetes, gallstones, breathing problems, and certain cancers.

That is why maintaining a healthy weight is so important: it helps you lower your risk for developing these problems, helps you feel good about yourself, and gives you more energy to enjoy life.

Important Notes:

• BMI is a screening tool and is not intended to diagnose disease or illness.
• BMI may not be accurate for athletes, pregnant women, elderly, and others.
• Always consult with a healthcare professional for personalized health advice.
• BMI should be used in conjunction with other health assessments.
• Individual results may vary based on muscle mass, bone density, and overall body composition.

Medical Disclaimer: This BMI calculator is for educational and informational purposes only and should not be used for medical diagnosis. The information provided should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. Please consult with a healthcare professional for personalized medical advice.