Fix – IndentationError: unexpected indent in Python

Hope you have found the right article to learn about the ERROR “IndentationError: unexpected indent” in Python. Unlike another language that uses braces {} or keywords to delimit blocks of code, Python uses whitespace indentation. If any mistake in whitespaces can lead to this error

What Causes an Indentation Error?

An IndentationError occurs when Python encounters an unexpected level of indentation, meaning the spaces or tabs at the beginning of a line don’t match the expected pattern. This error can disrupt the execution of your program and needs to be fixed for your code to run.

Let’s learn about the common causes and fixes.

1. Mismatched Indentation

A line of code is either over-indented or under-indented relative to the previous line, breaking the logical structure.


def greet(name):
    print("Hello, " + name)
     print("Welcome!") # This line has an unexpected indent



    print("Welcome!") # This line has an unexpected indent
IndentationError: unexpected indent

Fix: Ensure all lines in the same block have the same level of indentation(I have given 4 whitespaces).

def greet(name):
    print("Hello, " + name)
    print("Welcome!") # Corrected indentation



Hello, test_name

2. Mixing Tabs and Spaces

Python’s interpreter can get confused when tabs and spaces are mixed for indentation, leading to an IndentationError.


Assume you have indented the first line with spaces and the second line with a tab, which may not be visually distinguishable in some editors but is syntactically significant in Python.

Fix: Stick to either spaces or tabs for indentation, with PEP 8 recommending 4 spaces.

3. Incomplete Blocks

Starting a new block (e.g., after if, for, def) without any following indented line, then accidentally indent a line that should not be part of the block.


for i in range(5): 

print(i) # This line should be indented

Fix: Indent the lines that belong to the block correctly.

for i in range(5): 

    print(i) # Correctly indented

4. Copy-Paste Issues

Cause: Copying code from various sources might mix different indentation styles, leading to inconsistency.

Fix: Re-indent the pasted code using your text editor’s indentation feature or manually adjust the indentation.

Tips for Avoiding Indentation Errors

Understand Python’s Indentation Syntax

  • Recognize that Python uses indentation to define code blocks
  • Each level of indentation should be consistent throughout the block. This means if you start a block with 4 spaces, continue to use 4 spaces for that block.

Use Spaces Over Tabs (Or Stick to One)

  • The Python style guide (PEP 8) recommends using 4 spaces per indentation level. While Python 3 allows for mixing tabs and spaces, it’s best to choose one method and stick with it to avoid confusion. Using spaces is the recommended approach for maximum compatibility and readability.

Configure Your Text Editor

  • Set up your text editor or IDE to insert spaces whenever the tab key is pressed. This ensures consistency and prevents accidental mixing of tabs and spaces.
  • Many editors also offer features to visualize whitespace characters, making it easier to identify inconsistencies.

Utilize Linting Tools

  • Linting tools like flake8, pylint, or black can automatically detect and sometimes even fix indentation errors and other stylistic issues.

Format Code Automatically

  • Auto-formatting tools such as autopep8 or black can automatically format your Python code according to PEP 8, including fixing indentation levels.

Review Code Blocks Carefully

  • Pay extra attention when starting a new block of code (e.g., after an if statement, for loop, function definition, etc.). Make sure that the indentation level of your code correctly reflects its logical structure.


Indentation errors are the most commonly seen error in Python. Understanding how Python uses indentation and following best practices can help avoid these errors and keep your code clean and readable.

Happy Learning !!

Jerry Richard
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