How To Write A Helper Function In Python

In Python, writing a helper function is essential to make your code cleaner, more readable, and reusable. Helper functions, also known as utility functions, are small, specific functions that do one thing well and can be used in multiple parts of your code. In this step-by-step tutorial, we will learn how to write a helper function in Python.

Step 1: Identify the Purpose and Scope of the Helper Function

The first thing to do is identify what problem the helper function will solve. This will help you to better understand its purpose and scope. To do this, try to find a specific purpose or repetitive task that is duplicated in multiple areas throughout your code.

For example, let’s assume we have a program that performs various calculations and in many instances, we want to convert a number value from one unit to another (e.g., kilometers to miles, kilograms to pounds). In this case, we can create a helper function to perform these conversions.

Step 2: Define the Function

Once you have identified the purpose and scope of your helper function, it’s time to define the function. To do this, use the def keyword followed by the function’s name, a pair of parentheses including any input parameters, and a colon.

In our example, we want to create a helper function to convert kilometers to miles. To do this, we can define a function called convert_kilometers_to_miles() and pass a parameter called kilometers:

Step 3: Write the Function Body

Inside the helper function, you’ll write the code that will perform the desired action. In our example, we’ll complete the conversion from kilometers to miles by multiplying the kilometers parameter by the conversion factor (0.621371).

Step 4: Return the Result

The helper function will usually need to return a value to the caller. In this case, we want to return the result of the conversion. To do this, use the return keyword followed by the value you want to return.

Step 5: Use the Helper Function

Now that we have created the helper function, we can use it in various parts of our program. In the example, we would call the convert_kilometers_to_miles() function and pass the number of kilometers as an argument:

Here is the full code used in this tutorial:


10 kilometers is equal to 6.21371 miles.


In conclusion, creating helper functions in Python is an essential skill for effective programming. It will make your code more readable, maintainable, and modular. By following these steps, you can create helper functions to perform specific tasks and use them in different parts of your code.