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In this article I’m going to show how to calculate BMI. So, let’s get started.

## What is BMI?

BMI stands for body mass index and this is one of the anthropometric measurements that we collect during a health assessment along with other measurements such as skin fold thickness High weight and so on. Now BMI scores are really helpful because they allow us to screen patients for potential health problems.

## BMI Calculation

In this article, I’m going to show you how to calculate this number manually. First what you want to do is to collect the patient’s weight and height. Then once you have that you want to use a formula and plug in the information you have into whatever formula you want to use. Now the formula that you use is the same for adults and children male or female. But it depends on which measurement system you’re using.

## Imperial System vs Metric Unit

If you are using the imperial system such as pounds and inches, you’re going to use below mentioned formula.

BMI = 730 X (weight (in pounds/ Height^{2} (in inches))

But if you are using the metric units like kilograms and meters you will use the below mentioned formula.

BMI = (weight (in kilogram)/ Height^{2} (in meters)

### Example of Imperial Unit

In this example we’re going to use imperial formula because our measurements are in imperial units. A patient ways 167 pounds and they have a height of 6 feet and because we’re dealing with pounds and feet we can use imperial formula. But notice in the height part it needs to be in inches. So quickly what we need to do is we need to convert six feet into inches. And to do that you want to ask yourself how many inches are in one foot. We know that there are 12 inches in one foot so what we’re going to do is we’re going to multiply 12. by 6 and that gives us 72. So 6 feet is equivalent to 72 inches. Now we are ready to use our formula. So, first let’s plug in our weight which was 167 pounds so 167 and we are going to divide that into the height in inches but it’s going to be squared so don’t forget to bring down your square part. Because that’s the part you could easily forget so we’re going to put in 72 inches. That’s what we just figured out with our conversion and we’re going to square that so we’re going to put a little two There. To Remind us we’re going to multiply that by 703. So let’s go ahead and square this out when we say 72 squared that gives us 5184. I’m going to put 167 up there bring that down. So we don’t forget our little 703 because I would really throw off our equation so 167 divided by 5184 that gives us 0.032214. It literally keeps going on so we’re going to round to the fourth decimal point which is the Ten thousandths place now round how your professor wants you around. So, follow their rounding rules but we’re going to round to the fourth decimal place which will give us 0.0322. It makes things a little bit simpler and then we’re going to multiply that by seven hundred and three so when we multiply all that out we get 22.6366 and we’re going to round our BMI to that first decimal place which is the tenths place. Whenever we do that we get a BMI of 22.6 and that is our answer.

### Example of Metric Unit

Our next patient weighs 64.5 kilograms and they have a height of 1.65 meters. So, we’re dealing with kilograms and meters therefore we can use metric formula right here. This formula is a little bit different than the previous one because we don’t have to multiply by 703 so that’s one less step that we have to take. It’s a little bit simpler. We are going to plug it in so our patients weight in kilograms is 64.5 so 64.5. Our height is in meters and they had a height of 1.65 meters and remember don’t forget to square so we’re going to square it. Let’s go ahead and square that out so 1.65 squared gives us 2.7225. We are going to bring down our 64.5 and we’re going to just divide that out. Whenever we divide that out we’re going to get 23.6914. We are going to round to our nearest tenth that first decimal point and that’s going to give us 23.7 as the BMI of our patient.

## Interpretation of BMI Score

Now how do we interpret these BMI scores that we get. Once you have the BMI number you can see which category the patient fits in as per the CDC’s guidelines and these are the same for both adult females and males.

Therefore in our first example that we worked our patient’s BMI was 22.6 which falls into a healthy weight category.

Because, you can see here if the BMI is below 18.5 that’s considered underweight if it’s 18.5 to 24.9 that’s a healthy weight it if it’s 25 to 29.9 that’s overweight and anything 30 and above is considered obesity. If you want to know the BMI ranges for children and teens the CDC publishes individual charts for boys and girls. So that wraps up this article on how to calculate a BMI .