Python input() and Type Conversion: int(), float(), str()

So far your programs have only talked (with print). Now they’ll listen. The input() function pauses your program, waits for the user to type a line and press Enter, and gives you back what they typed:

name = input("What is your name? ")
print(f"Hello, {name}!")

Run that in real Python and it asks for your name, then greets you. (You’ll do exactly this in the challenges below, where we feed the input for you.)

The one rule that catches everyone

input() always gives you a string — even if the user types a number. So if you try to do math with it directly, it breaks. Watch:

age = "25"
print(age + 5)

TypeError

That "25" is what input() would have handed you: text, not a number. Adding text and a number raises TypeError.

The fix: convert with int() and float()

To turn a string into a number, wrap it in int() (whole numbers) or float() (decimals):

print(int("25"))

25

Now the math works:

age = int("25")
print(age + 5)

30

For decimals, use float():

print(float("3.14"))

3.14

So the real pattern for reading a number from the user is int(input()) or float(input()) — read the text, then convert it.

Going the other way: str()

str() converts a number into text, which lets you join it with +:

print("Total: " + str(100))

Total: 100

(Most of the time an f-string is easier — f"Total: {100}" — but str() is good to know.)

Putting it together

Convert the inputs, do the work, then show the result with an f-string:

price = int("50")
quantity = int("3")
print(f"You owe {price * quantity} rupees")

You owe 150 rupees

Now you try — with real input()

The challenges below run your input() code for real. Write the program, press Run tests, and we’ll feed it sample inputs and check what it prints.

Edge cases worth remembering

• int("3.5") raises ValueError — int() won’t parse a decimal string. Use float("3.5") instead (then int() on the float if you want to drop the fraction).
• int() ignores surrounding spaces (int(" 25 ") is 25) but not stray characters (int("25kg") raises ValueError).