How to Convert a String to an Integer in Python

Convert a string to an integer in Python with the built-in int() function: int("42") returns 42. Handles different bases and bad input too.

Jimmy S.

Jun 28, 2026 · Updated Jul 15, 2026 · 2 min read

The int() function

text = "42"
number = int(text)
print(number + 8)   # 50

Once converted, the value behaves like any other integer, so you can do arithmetic with it instead of string concatenation.

print(int("ff", 16))   # 255
print(int("1010", 2))  # 10

The second argument tells Python the base of the text, which is handy for parsing hexadecimal or binary strings.

try:
    number = int("abc")
except ValueError:
    print("That is not a valid number.")

Wrapping the call in try/except stops a single bad value from crashing your program.

Trying to convert a decimal string directly. int("3.5") fails — use int(float("3.5")) to get 3.
Expecting commas to be ignored. int("1,000") raises an error; remove the comma first with replace.

Because int() only parses whole numbers. Convert the text to a float first and then to an int: int(float("3.5")), which gives 3.

Use text.strip().isdigit() for plain positive integers, or simply try the conversion inside a try/except block.

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