ValueError: invalid literal for int() with base 10

What you see

price = "12.50"
print(int(price))

Traceback (most recent call last):
  File "/home/me/project/main.py", line 2, in <module>
    print(int(price))
          ~~~^^^^^^^
ValueError: invalid literal for int() with base 10: '12.50'

What it means

int() turns text into a whole number, and it accepts only digits, with an optional sign and spaces around them. "12.50" has a decimal point, so it is not an integer literal. The text in quotes at the end of the message is exactly what int() received.

"Base 10" is the default: ordinary decimal numbers. int("ff", 16) reads hexadecimal.

Why it happens

• A decimal number, as in the example: "12.50", "3.0".
• An empty string, the message then ends in ''. Pressing Enter at an input() prompt, or a blank cell in a CSV file, gives one.
• Thousands separators or units: "1,000", "5 kg", "$20".
• Text that is not a number at all, such as a header row read as data.

How to fix it

For a decimal, convert with float() first; int() then drops the fraction:

print(int(float("12.50")))   # 12

For money, keep it exact with decimal.Decimal:

from decimal import Decimal
print(Decimal("12.50"))

Strip separators before converting, and catch the error where input can be anything:

text = "1,000".replace(",", "")
try:
    n = int(text)
except ValueError:
    print("not a whole number:", repr(text))

How each Python version words it

Run on CPython 3.9.6, 3.10.22, 3.11.17, 3.12.15, 3.13.17, 3.14.9 and 3.15.1, on October 25, 2026.

The wording is the same in every version here.