Skip to main content

How to Check If a Number Is Positive in Python

Determining whether a number is positive, negative, or zero is a fundamental operation in programming logic. Whether you are validating user input, calculating physical properties (like speed or mass), or managing financial data, checking the sign of a number is essential.

This guide explains how to check if a number is positive using Python's conditional statements and how to handle different numeric types like integers and floats.

Understanding Positive Numbers​

In mathematics and computing, a positive number is any number strictly greater than zero (> 0).

  • Examples: 1, 5, 100, 0.5, 3.14.
  • Zero (0) is typically considered neither positive nor negative (neutral), though definitions can vary in specific contexts (e.g., "non-negative" includes zero).

Method 1: Basic Positive Check (Greater Than Zero)​

To check if a number is positive, use the greater-than operator (>).

number = 10

# ✅ Correct: Check if strictly greater than 0
if number > 0:
    print(f"{number} is a positive number")

Output:

10 is a positive number

If you change the number to -5 or 0, the code inside the if block will simply not execute.

Method 2: Handling Zero and Negative Numbers​

In most real-world scenarios, you need to know exactly which category a number falls into: positive, negative, or zero. You can handle all three cases using an if-elif-else structure.

number = 0

if number > 0:
    print(f"{number} is a positive number")
elif number == 0:
    print(f"{number} is zero")
else:
    # If it's not positive and not zero, it must be negative
    print(f"{number} is a negative number")

Output:

0 is zero

Test Cases:

  • If number = 5: Output is "5 is a positive number".
  • If number = -5: Output is "-5 is a negative number".
  • If number = 0: Output is "0 is zero".
note

Order matters. If you used >= 0 (greater than or equal to) in the first check, zero would be classified as positive in that context. Usually, strict inequality (>) is preferred to distinguish zero separately.

Handling Different Numeric Types (Int vs Float)​

Python handles comparison operators seamlessly across different numeric types. You do not need to convert integers to floats or vice versa to check their sign.

Checking Floating-Point Numbers​

Decimals work exactly the same way.

# A positive float
num_float = 3.14

if num_float > 0:
    print(f"{num_float} is a positive number")

# A negative float
num_negative_float = -2.5

if num_negative_float < 0:
    print(f"{num_negative_float} is a negative number")

Output:

3.14 is a positive number
-2.5 is a negative number

Mixing Types​

You can compare an integer variable against 0.0 (float zero) or a float variable against 0 (integer zero) without issues.

val_a = 10    # int
val_b = 0.0   # float

# Python automatically handles the type conversion for comparison
if val_a > val_b: 
    print("10 is greater than 0.0")

Output:

10 is greater than 0.0

Conclusion​

To check if a number is positive in Python:

  1. Use if number > 0: for a standard positive check.
  2. Use elif number == 0: if you need to handle zero as a distinct case.
  3. Rely on Python's dynamic typing to handle both integers (10) and floats (3.14) with the same logic.

Table of Contents