Altcademy - a Forbes magazine logo Best Coding Bootcamp 2023

How to get length of list in Python

Understanding Lists in Python

The Concept of Lists

Before we dive into how we can find the length of a list in Python, it's important to understand what a list is. Imagine you have a shopping list. It contains items that you need to buy from the store. In Python, a list is similar. It contains items, which can be numbers, strings, or even other lists.

The items in a Python list are ordered and changeable. This means that the items have a fixed order unless you change it, and you can change, add, or remove items after the list is created.

Here's an example of a list in Python:

shopping_list = ['apples', 'bananas', 'cherries', 'dates', 'elderberries']

The Importance of Knowing the Length of Lists

Now that you understand what a list is, you might be wondering why we need to know the length of a list. Going back to our shopping list analogy, knowing the length of the list can give you an idea of how many items you need to buy.

In programming, knowing the length of a list can be helpful for many reasons. It can help you to control a loop (a way to repeat the same code several times), to verify data (checking if the list contains the expected number of items), and much more.

How to Find the Length of a List

So, how do we find the length of a list in Python? Python provides a built-in function called len() that returns the number of items in a list (or any other iterable).

Here's how you can use it with our shopping list:

shopping_list = ['apples', 'bananas', 'cherries', 'dates', 'elderberries']

This will output 5, because there are five items in our shopping list.

Understanding the len() Function

The len() function is a built-in function in Python. "Built-in" means that it comes with Python, and you can use it without having to install or import anything.

The len() function takes one argument, which is the list (or other iterable) that you want to find the length of. An "argument" in programming is a value that you provide to a function so it can do its job.

Here's another example:

numbers = [1, 2, 3, 4, 5]

This will output 5, because there are five numbers in the list.

The Power of len() Function

The len() function is not limited to lists. You can also use it with strings, dictionaries, sets, and other iterable objects in Python.

Here's how you can use it with a string:

greeting = "Hello, world!"

This will output 13, because there are thirteen characters in the string (including the comma and the space).


In conclusion, the len() function is a simple yet powerful tool in Python. Like a ruler in the physical world, it measures the length of various objects in the Python world, from lists to strings and more.

Remember the excitement of measuring things when you were a kid? The len() function brings that excitement into programming. It's as if you're embarking on a new adventure every time you use the len() function, discovering the size of new territories in the world of Python.

So go ahead, start your adventure, and explore the world of Python with the len() function. Happy coding!