Python .extend()

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jeri1991
Published Jun 4, 2021Updated Jul 14, 2025
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In Python, the .extend() method adds the elements of an iterable (like a list, string, or tuple) to the end of the current list. Unlike .append(), which adds the entire object as a single element, .extend() adds each element individually.

This makes .extend() especially useful for combining lists or incorporating multiple values into an existing list.

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Syntax

list.extend(iterable)

Parameters:

  • iterable: An iterable (like a list, tuple, or string) whose elements are to be added to list.

Return value:

The .extend() method changes the list in place and returns None.

Example 1: Extending a List with Another List

This example uses .extend() to add the items from the grocery_new list to the end of the grocery list:

grocery = ['blueberries', 'eggs', 'artichoke']
grocery_new = ['milk', 'cookies']


grocery.extend(grocery_new)


print(grocery)

Here is the output:

['blueberries', 'eggs', 'artichoke', 'milk', 'cookies']

Example 2: Extending a List with a Tuple

This example uses .extend() to add the items from the targets tuple to the end of the to_do_list list:

to_do_list = ['respond to email', 'check github']
targets = (4, 1, 6, 20)


to_do_list.extend(targets)


print(to_do_list)

Here is the output:

['respond to email', 'check github', 4, 1, 6, 20]

Codebyte Example: Extending a List with a String

This example uses .extend() to add the characters of a string to the end of the letters list:

Code
Output
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Frequently Asked Questions


1. What is the difference between .append() and .extend()?


    

  • .append() adds the entire object as a single element.
    • 

  • .extend() adds elements one by one from the iterable.
    • 



2. Does .extend() return a new list?


No. .extend() modifies the list in place and returns None.


3. What happens if I pass a non-iterable object to .extend()?


If you pass a non-iterable object to .extend(), you’ll get a TypeError.


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  • Career path
    Data Scientist: Machine Learning Specialist
    Machine Learning Data Scientists solve problems at scale, make predictions, find patterns, and more! They use Python, SQL, and algorithms.
    • Includes 27 Courses
    • With Professional Certification
    • Beginner Friendly.
      95 hours
  • Course
    Learn Python 3
    Learn the basics of Python 3.12, one of the most powerful, versatile, and in-demand programming languages today.

    • With Certificate
    • Beginner Friendly.
      24 hours