Fix Python ValueError: invalid literal for int() with base 10 (2025 Guide)

Posted on: March 19, 2025

Encountered a "ValueError: invalid literal for int() with base 10" in Python? This error occurs when you try to convert a string to an integer using `int()`, but the string isn’t a valid integer. Let’s fix it fast in this 2025 guide!

What Causes "ValueError: invalid literal for int() with base 10"?

This error happens when Python’s `int()` function can’t parse a string into a base-10 integer. Common causes include:

• Non-Numeric Strings: Trying to convert letters or symbols (e.g., "abc") to an integer.
• Unexpected Characters: Strings with spaces, decimals, or special characters (e.g., "12.5", " 10 ").
• User Input Issues: Receiving unvalidated input that isn’t a clean integer.

Check this demo (run in a Python environment):

# This will trigger "ValueError: invalid literal for int() with base 10"
value = "12.5"
number = int(value)  # Fails because "12.5" isn’t an integer

Running this throws the error because `12.5` is a float, not an integer.

How to Fix It: 3 Solutions

Let’s resolve this error with practical steps:

(Diagram: Developer tries int() on invalid string, gets error, validates input, runs successfully.)

Solution 1: Clean the Input

Ensure the string is a valid integer before conversion:

# Wrong
value = "12.5"
number = int(value)

# Fixed
value = "12"  # Use a valid integer string
number = int(value)  # 12

Strip decimals or non-numeric characters to make the string convertible.

Solution 2: Handle Floats Separately

Convert to float first if decimals are possible, then to int if needed:

# Wrong
value = "12.5"
number = int(value)

# Fixed
value = "12.5"
number = int(float(value))  # Converts "12.5" to 12

Use `float()` to handle decimal strings, then `int()` to truncate to an integer.

Solution 3: Use Try-Except

Wrap the conversion in a `try-except` block for robust error handling:

# Wrong
value = "abc"
number = int(value)

# Fixed
value = "abc"
try:
    number = int(value)
except ValueError:
    print("Caught a ValueError: invalid literal for int()")
    number = 0  # Fallback value

`try-except` catches the error and provides a fallback, preventing crashes.

Quick Checklist

• Non-numeric string? (Clean it first)
• Decimal numbers? (Use `float()` then `int()`)
• Unpredictable input? (Use `try-except`)

Conclusion

The "ValueError: invalid literal for int() with base 10" in Python is straightforward to fix once you validate your input. With these 2025 solutions, your code will handle conversions smoothly. Got another Python error? Let us know in the comments!