How to Subtract Two Numbers in Python

To subtract two numbers in Python, put the minus operator between them: a - b. It works the same way for integers and floats, and the result is negative when the second number is bigger:

difference = 1299.99 - 150.00   # 1149.99

Every output below comes from Python 3.12.5 in a real Command Prompt, using US prices in dollars and 2026 dates.

In this tutorial, I’ll cover user input, -=, operator.sub, float cents, negative results and functions.

Subtract two numbers with the minus operator

Save this as subtract_minus.py and run python subtract_minus.py in Command Prompt:

price = 1299.99      # laptop list price in USD
discount = 150.00
print("Sale price:", price - discount)

print(100 - 40)      # int - int   -> int
print(40 - 100)      # order matters: negative result
print(10 - 2.5)      # int - float -> float
print(type(10 - 4), type(10 - 4.0))

Output:

Sale price: 1149.99
60
-60
7.5
<class 'int'> <class 'float'>

Python follows the same type rules when you’re adding two numbers in Python: two ints give an int, and any float in the mix gives a float.

How do you subtract two numbers entered by the user?

input() always returns text, so convert both values before subtracting. I use float() for money; the Python input() function guide covers prompts in more detail:

balance = float(input("Gift card balance (USD): "))
spent = float(input("Amount spent (USD): "))
left = balance - spent
print(f"Remaining balance: ${left:.2f}")

Output:

Gift card balance (USD): 250
Amount spent (USD): 87.45
Remaining balance: $162.55

Forget the conversion and Python refuses to subtract two strings:

a, b = "250", "87"       # what input() gives you: text
try:
    print(a - b)
except TypeError as err:
    print("TypeError:", err)
print(int(a) - int(b))

Output:

TypeError: unsupported operand type(s) for -: 'str' and 'str'
163

Use int() for whole numbers. If the text has commas or dollar signs, clean it first, as shown in converting a string to a float in Python.

Subtract in place with -= and operator.sub

budget -= 1200.50 is short for budget = budget - 1200.50. See increment and decrement operators in Python for why there’s no --:

import operator
from functools import reduce

budget = 5000.00                 # Q1 2026 marketing budget
budget -= 1200.50                # January ads
budget -= 845.25                 # February trade show
print(f"Left after February: ${budget:,.2f}")

print(operator.sub(5000, 1200))  # same as 5000 - 1200
print(reduce(operator.sub, [5000, 1200, 845, 300]))   # 5000-1200-845-300

Output:

Left after February: $2,954.25
3800
2655

operator.sub(a, b) is the function version of a - b. It’s handy when another function needs a callable, like reduce() in Python, which subtracts a whole list from left to right.

Why does float subtraction give 0.19999999999999998?

Floats are binary, so most decimal fractions aren’t stored exactly and price math can drift:

from decimal import Decimal

print(0.3 - 0.1)
print(19.99 - 9.99)
print(round(19.99 - 9.99, 2))
print(f"${19.99 - 9.99:.2f}")

total = Decimal("19.99") - Decimal("9.99")
print(total, Decimal("100.00") - Decimal("0.01"))
print(Decimal(19.99) - Decimal(9.99))    # built from floats: the error comes along

Output:

0.19999999999999998
9.999999999999998
10.0
$10.00
10.00 99.99
9.999999999999998223643160600

For display, round(x, 2) or an f-string is enough; see printing 2 decimal places in Python. For money you store or total up, use Decimal built from strings. Built from floats, it keeps the error.

Subtract two numbers in a function and handle negative results

A function makes subtraction reusable. Add abs() when only the gap matters:

def subtract(a, b):
    """Return a minus b."""
    return a - b

def difference(a, b):
    """Return the gap between a and b, never negative."""
    return abs(a - b)

print(subtract(72, 58))        # Austin high vs low, Oct 19, 2026
print(subtract(58, 72))
print(difference(58, 72))
print(subtract(2026, 1776), "years since 1776")

Output:

14
-14
14
250 years since 1776

Your function must return the result rather than print it, or the caller gets None; the Python return statement shows why. More on abs() is in absolute value in Python.

Ready for the other arithmetic basics? Pick one:

• Divide two numbers in Python
• Add two numbers without the + operator
• Make a calculator in Python
• Calculate simple interest in Python

Frequently asked questions