IndentationError: unexpected indent

IndentationError: unexpected indent means Python found a line with extra whitespace that doesn’t match the expected indentation level. Python uses indentation to define code blocks — consistency is critical.

What It Means

Unlike most languages that use braces or keywords, Python uses indentation to determine which statements belong to which block. Any inconsistency — extra spaces, missing spaces, or a mix of tabs and spaces — triggers this error.

Why It Happens

• Mixing tabs and spaces (the most common cause)
• Extra spaces at the start of a line that shouldn’t be indented
• Inconsistent indentation levels within the same block
• A code editor that inserts tabs when you press Tab, while the rest of the file uses spaces

How to Fix It

Step 1: Use spaces consistently (4 spaces per level)

# BAD — mixing tabs and spaces
def hello():
    print("Hello")  # 4 spaces
	print("World")  # 1 tab (looks aligned but isn't)

# GOOD — all spaces (4 per level)
def hello():
    print("Hello")
    print("World")

Step 2: Configure your editor to convert tabs to spaces

Most editors have a setting for this:

VS Code: "editor.insertSpaces": true, "editor.tabSize": 4
PyCharm: Settings → Code Style → Python → "Use tab character" unchecked
Sublime: "translate_tabs_to_spaces": true

Step 3: Re-indent the entire file

Run the reindent script or use an auto-formatter:

# Install and run Black (auto-formatter)
pip install black
black your_file.py

# Or use autopep8
pip install autopep8
autopep8 --in-place your_file.py

Step 4: Check for mixed indentation in your code

# BAD — inconsistent levels
if True:
    print("Indented OK")
      print("One extra space")  # unexpected indent

# GOOD
if True:
    print("Indented OK")
    print("Also OK")

Step 5: Look for unexpected indentation after comments

A stray space before a line that starts a new block can cause this:

# BAD
def my_func():
    pass
 print("outside function")  # This line has a leading space!

# GOOD
def my_func():
    pass
print("outside function")