# Simple Guide to write a BMI Calculator app in Python

**What is BMI?**

The Body Mass Index (BMI) is a measurement of a person's leanness or corpulence based on their height and weight and is intended to quantify tissue mass. It is widely used as a general indicator of whether a person has a healthy body weight for their height. Specifically, the value obtained from the calculation of BMI is used to categorize whether a person is underweight, normal weight, overweight, or obese depending on what range the value falls between.

**Come on to build ****a ****simple BMI Calculator**

## How does it work?

A BMI Calculator will take in the height and weight individually and will calculate the BMI of the user.

**Body mass index (BMI) is a measure of body fat based on height and weight.**

Based on the BMI of the individual, it will print a statement stating the overall health case of the user.

**Coding Time :)**

The first thing we need to do is to ask the user about their height & weight.

```
height = float(input("Enter your height in cm: "))
weight = float(input("Enter your weight in kg: "))
```

We used float() to convert the input string to float so that we can perform calculations with it.

Next, we have to calculate the BMI.

**The formula to calculate BMI is: **

So, the implementation of this formula in python will be:

`BMI = weight / (height/100)**2`

Here we will be dividing the **height** by 100 to convert the **centimeters **into **meters**.

to print BMI:

`print(f"Your BMI is {BMI}")`

Now we have to print a statement to state the current health case of the user based on their **BMI**.

And to implement this classification we use a simple if-else condition:

```
if BMI <= 18.4:
print("You are underweight !")
elif BMI <= 24.9:
print("You are healthy :)")
elif BMI <= 29.9:
print("You are over weight !")
elif BMI <= 34.9:
print("You have obesity class 1 !")
elif BMI <= 39.9:
print("You have obesity class 2 !")
else:
print("You have obesity class 3 !")
```

The output will be:

if BMI is

**less than or equal to 18.4**then**You are underweight !**will be printed.if BMI is

**less than or equal to 24.9**then**You are healthy :)**will be printed.if BMI is

**less than or equal to 29.9**then**You are over weight !**will be printed.if BMI is

**less than or equal to 34.9**then**You have obesity****class 1 !**will be printed.if BMI is

**less than or equal to 39.9**then**You have obesity****class 2**! will be printed.if BMI none of the above are true then

**You have obesity class 3 !**will be printed.

That's it, I hope this article was worth reading and helped you acquire new knowledge no matter how small.

Feel free to check up on the __notebook__. You can find the results of code samples in this post.

## Comments