Count the Number of Elements in a Python List

The len() function can be used to count the number of elements in a Python list:

len(my_list)

3 Examples of Counting the Number of Elements in a List

Example 1: List that Contains Strings

To start with a simple example, create a list that contains 5 names:

names_list = ["Jeff", "Ben", "Maria", "Sophia", "Rob"]

print(names_list)

Run the script above, and you’ll get the following list:

['Jeff', 'Ben', 'Maria', 'Sophia', 'Rob']

You can then use the len() function in order to count the number of elements in the list:

names_list = ["Jeff", "Ben", "Maria", "Sophia", "Rob"]

number_of_elements = len(names_list)

print(number_of_elements)

Once you run the script in Python, you’ll get the following count:

5

Extend the list by additional 3 names, and then recount the number of elements:

names_list = ["Jeff", "Ben", "Maria", "Sophia", "Rob"]
names_list.extend(["Laura", "Elizabeth", "Justin"])

number_of_elements = len(names_list)

print(number_of_elements)

Here is the new count:

8

Example 2: List that Contains Numeric Data

Now create a list with numeric data:

numbers_list = [7, 22, 35, 28, 42, 15, 30, 11, 24, 17]

print(numbers_list)

Here is the list that you’ll get:

[7, 22, 35, 28, 42, 15, 30, 11, 24, 17]

Use the len() function to count the number of elements in the list:

numbers_list = [7, 22, 35, 28, 42, 15, 30, 11, 24, 17]

number_of_elements = len(numbers_list)

print(number_of_elements)

The result:

10

Example 3: List of Lists

What if you want to count the number of elements in a list of lists?

For instance, let’s create the following list of lists:

people_list = [
    ["Jon", "Smith", 21],
    ["Mark", "Brown", 38],
    ["Maria", "Lee", 42],
    ["Jill", "Jones", 28],
    ["Jack", "Ford", 55],
]

print(people_list)

You’ll now see this list of lists:

[['Jon', 'Smith', 21], ['Mark', 'Brown', 38], ['Maria', 'Lee', 42], ['Jill', 'Jones', 28], ['Jack', 'Ford', 55]]

Before you count all the elements, you’ll need to flatten the list of lists as follows:

people_list = [
    ["Jon", "Smith", 21],
    ["Mark", "Brown", 38],
    ["Maria", "Lee", 42],
    ["Jill", "Jones", 28],
    ["Jack", "Ford", 55],
]

flat_people_list = [i for x in people_list for i in x]

print(flat_people_list)

Here is how the flatten list would look like:

['Jon', 'Smith', 21, 'Mark', 'Brown', 38, 'Maria', 'Lee', 42, 'Jill', 'Jones', 28, 'Jack', 'Ford', 55]

Finally, you can use the script below to get the total count:

people_list = [
    ["Jon", "Smith", 21],
    ["Mark", "Brown", 38],
    ["Maria", "Lee", 42],
    ["Jill", "Jones", 28],
    ["Jack", "Ford", 55],
]

flat_people_list = [i for x in people_list for i in x]

number_of_elements = len(flat_people_list)

print(number_of_elements)

The result:

15