# Body Mass Index (BMI) Calculator

### What is BMI?

If you are considering bariatric surgery, you should first understand what determines a healthy weight. It’s more than just a number on your scale.

Body Mass Index (BMI) is:

• A number calculated from a person’s weight and height.
• A fairly reliable indicator of whether you’re at an appropriate weight for your height by estimating your body fat.
• An inexpensive and easy-to-perform method of screening for weight categories that may lead to health problems.

To calculate your BMI, your height and weight are entered into a mathematical equation and the resulting number reveals whether you’re underweight, normal weight, overweight, or obese. If your BMI is 25 or above — and you are not an athlete or you don’t have a muscular build — you could be at risk for numerous health conditions, and might be a candidate for bariatric surgery.

Body Mass Index (BMI) is a number calculated from a person’s height and weight that is used to determine how much of their body is composed of fat.

BMI Chart:
 Underweight Under 18.5 Normal 18.5 - 24.9 Overweight 25 - 29.9 Obese Class I 30 - 34.9 Obese Class II 35 - 39.9 Obese Class III over 40

### How is BMI Calculated?

BMI is calculated the same way for both adults and children.

The calculation is based on the following formulas:

## Formula and Calculation

Pounds & inches Formula: weight (lbs.) / [height (in)]2 x 703

Calculate BMI by dividing weight in pounds (lbs.) by height in inches (in) squared and multiplying by a conversion factor of 703.

Example: Weight = 150 lbs, Height = 5’5″ (65″)
Calculation: [150 ÷ (65)2] x 703 = 24.96

Kilograms & meters (or centimeters) Formula: weight (kg) / [height (m)]2

With the metric system, the formula for BMI is weight in kilograms divided by height in meters squared. Since height is commonly measured in centimeters, divide height in centimeters by 100 to obtain height in meters.

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

Source: Centers for Disease Control and Prevention