# How is Body Mass Index (BMI) calculated?

**Formula:**

Weight (lb) / [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

[Source: CDC]

For example, a woman weighs 150 pounds and her height is 5 feet 6 inches (66 inches):

150 lb x 705 = 105,750

105,750/66 = 1602

1602/66 = 24 BMI

Free BMI App - A new smartphone app from the National Institutes of Health can let your phone tell you. To get the free app, search “My BMI Calculator” on your phone today.

To find out your BMI, divide your weight in pounds by your height in inches multiplied by your height in inches. Take that number and multiply it by 703.

= mass(lb) / (height(in))² x 703

A BMI of less than 18.5 is considered “underweight.” A BMI between 18.5 and 24.9 is considered “normal weight.” A BMI of 25 to 29.9 is considered “overweight.” A BMI of 30 or greater is considered “obese.”

Morbid obesity is defined as having a body mass index (BMI) of more than 40. For men that equates to approximately 100 pounds overweight for women, 80 pounds overweight.

BMI Categories:

- Underweight = <18.5
- Normal weight = 18.5–24.9
- Overweight = 25–29.9
- Obesity = BMI of 30 or greater

To calculate your BMI measure your weight in pounds and height in inches; then multply the answer by 703

[Weight / (height x height)] x 703 = BMI

Your weight and height are measured. Then, your weight is converted to kilograms, and your height is converted to meters and then squared. Your BMI is calculated by dividing your body weight (in kilograms) by your height (in meters squared). The resulting number represents your BMI.

The formula for BMI is in metric units: kilograms per meter-squared.

If you don’t want to convert your height and weight to metric, there are multiple calculators on the web to use, or you can use the following non-metric formula: 704 times (X) pounds of body weight, divided by height in inches-squared.

The same formula is used for adult men and women of any age, but children are graphed on a different chart, and BMI is expressed as a percentile for that age or height.- Convert your weight in pounds to your weight in kilograms by dividing your weight in pounds by 2.2.
- Convert your height in inches to your height in meters by multiplying your height in inches -- not feet -- by 0.0254. (If you are 5 feet tall, your height is 60 inches, or 1.52 meters. If you are 6 feet tall, your height is 72 inches, or 1.83 meters.)
- Square your height in meters (that is, multiply your height in meters by itself).
- Divide your weight in kilograms by the number you obtained in the previous step.

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This formula is less daunting than it appears. To figure your BMI, follow these steps:

**1. Weigh yourself without your clothes.**Divide your weight in pounds by 2.2 to get your weight in kilograms. If you weigh 190 pounds:

190 ÷ 2.2 = 86 kilograms.

**2. Measure yourself without your shoes.**Then divide your height in inches by 39.4 to determine your height in meters. For example, if you are 5 feet 10 inches tall, you are 70 inches tall and your height in meters is

70 ÷ 39.4 = 1.78 meters.

To find the square of your height in meters, multiply this figure by itself:

1.78 x 1.78 = 3.2.

**3. Finally, divide the answer to No. 1 by the answer to No. 2:**

86 ÷ 3.2 = 26.8.

Your BMI is thus 26.8, or rather too close for comfort to the danger zone.

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Ideal Weight Calculator **(Body Mass Index)** is a reliable indicator of your body’s fitness level, and most importantly, your health risk. It works by calculating your weight and height and correlates it to your body fat level. To determine your BMI, you can calculate it by: ** **

**BMI = Weight (lbs) / (Height (in) x Height (in)) x 703**

To use a calculator to determine your BMI, go to:** **

http://www.weight-loss-plans-4-you.com/ideal-weight-calculator.html

For inches and pounds the formula is: [weight in lbs ÷ (height in inches)2] x 703

Divide your weight in pounds by your height in inches squared, and then multiply that answer by 703. For example if someone is 5’5” (65”) and 150 lbs the calculation would look like the following:

[150/(65)2] x 703 = 24.96

This is the formula we used on the show:

The Body Mass Index (BMI) is a measurement tool that compares your height to your weight and gives you an indication of whether you are overweight, underweight or at a healthy weight for your height.

BMI = ( Weight in pounds/ Height in inches x Height in inches.) x 703

OR

BMI= (Weight in kilograms/ Height in meters x Height in meters)

For example, if you are 5'5" (65 inches) and weigh 130lbs your BMI woud be:

(130 divided by 65 x 65) x 703 = 21.6

Therefore, a person who is 5'5" tall and weighs 130lbs would have a BMI of 21.6.

Body Mass Index can be calculated in the inches and pounds of the English measuring system (common in the United States) or the meters and kilograms of the metric system (common almost everywhere else).

In both cases, determining the result for adults first requires dividing the weight by the square of the height. For metric measurements, nothing else is required. For pounds and inches, the result must be multiplied by 703 to yield the final answer.

Here are examples.

A person who weighs 180 pounds and is 5 feet 8 inches tall has a BMI of 27.4. That's 180 divided by 68 times 68, multiplied by 703.

A person who weighs 99.79 kilograms and is 1.905 meters (190.50 centimeters) tall has a BMI of 27.5. That's 99.79 divided by 190.5 times 190.5.

Determine your weight, in pounds. Divide that number by the square of your height in inches. Multiply by 703. That is your body mass index. If you prefer the metric system, divide your weight in kilograms by height in meters, and you're done.

## Continue Learning about Body Mass Index (BMI)

### Body Mass Index (BMI)

Body Mass Index, or BMI is the customary method used to measure obesity. It's a calculation of your weight-to-height ratio and can provide insight into risk for diseases. It's been shown that for every five-point increase in BMI, ...

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.