Python Numbers Explained (int, float, complex)

Python has different number types for different kinds of values.

The three main built-in numeric types are:

int
float
complex

If you are just starting Python, you will use int and float most of the time. This page explains what each type means, how to recognize it, and a few common mistakes beginners run into.

What this page covers

Python has different number types for different kinds of values
The main built-in numeric types are int, float, and complex
Beginners mostly use int and float first
This page explains what each type is and how to identify it

What is an int in Python?

An int is a whole number.

It does not have a decimal point.

Examples of integers:

0
5
-3
100

Use int for things like:

counting items
list indexes
lengths
whole-number math

apples = 5
temperature_change = -3
year = 2024

print(apples)
print(type(apples))

Output:

5
<class 'int'>

What is a float in Python?

A float is a number with a decimal point.

Examples:

3.14
2.0
-0.5

Use float for values like:

measurements
averages
prices
division results

Even 2.0 is a float, because it includes a decimal point.

price = 19.99
average = 4.5
exact_two = 2.0

print(price)
print(type(price))
print(type(exact_two))

Output:

19.99
<class 'float'>
<class 'float'>

What is a complex number in Python?

A complex number has:

a real part
an imaginary part

In Python, the imaginary part uses j.

Examples:

2 + 3j
5j
-1 + 0j

Complex numbers are real Python number types, but they are much less common in beginner programs.

number = 2 + 3j

print(number)
print(type(number))

Output:

(2+3j)
<class 'complex'>

If you are new to Python, it is completely normal to focus on int and float first.

How to check a number type

Use the type() function to see the type of a value.

print(type(5))
print(type(3.14))
print(type(2 + 3j))

Output:

<class 'int'>
<class 'float'>
<class 'complex'>

This is very useful when you are debugging a program and want to see what kind of value you actually have.

Basic operations with numbers

You can do basic math with Python numbers:

addition with +
subtraction with -
multiplication with *
division with /

print(5 + 2)
print(5 - 2)
print(5 * 2)
print(5 / 2)

Output:

A few important rules:

adding two int values usually gives an int
using a float in an expression usually gives a float
division with / returns a float

int and float together

Python can use int and float in the same expression.

When that happens, the result usually becomes a float.

print(5 + 2.0)
print(10 - 3.5)
print(4 * 1.5)

Output:

7.0
6.5
6.0

This is normal. Python keeps the decimal information instead of removing it.

Converting between number types

Use int() to convert a value to an integer.

Use float() to convert a value to a float.

print(int(3.9))
print(float(5))
print(int("10"))
print(float("3.14"))

Output:

Important: int(3.9) does not round. It removes the decimal part.

If you want rounding behavior, use round().

print(int(3.9))
print(round(3.9))

Output:

3
4

If you are converting text input into numbers, these guides can help:

Important beginner note about division

This is one of the most common beginner surprises:

print(10 / 2)
print(10 // 3)

Output:

5.0
3

Why?

/ returns a float
// does floor division

So:

10 / 2 gives 5.0
10 // 3 gives 3

Use / when you want normal division.

Use // when you want a whole-number result.

Common beginner mistakes

Here are some common problems when working with numbers in Python.

1. Confusing numbers with strings from input()

The input() function returns text, not a number.

age = input("Enter your age: ")
print(type(age))

If the user enters 25, the type is still str, not int.

To fix this, convert the value:

age = int(input("Enter your age: "))
print(age)
print(type(age))

If the text cannot be converted, you may get a ValueError: invalid literal for int() with base 10.

2. Expecting int(3.9) to round up

This does not round:

print(int(3.9))

Output:

If you want rounding, use round() instead.

3. Forgetting that / returns a float

Many beginners expect this:

print(10 / 2)

to return 5.

But it returns:

5.0

That is correct behavior in Python.

4. Trying to mix strings and numbers with +

This causes an error:

age = 25
print("Age: " + age)

Python cannot join text and a number directly like that.

Fix it by converting the number to a string:

age = 25
print("Age: " + str(age))

Or use commas in print():

age = 25
print("Age:", age)

When to use each number type

Use int when you need:

counts
positions
indexes
whole numbers

Use float when you need:

decimal values
measurements
prices
averages

Use complex only when you specifically need imaginary numbers.

For most beginner programs:

int is very common
float is also very common
complex is much less common

FAQ

What is the difference between int and float in Python?

An int is a whole number. A float is a number with a decimal point.

Why does Python return 5.0 instead of 5?

The / operator returns a float, even when the result looks like a whole number.

Does int() round a number?

No. int() removes the decimal part. Use round() if you want rounding.

What does j mean in a complex number?

In Python, j represents the imaginary part of a complex number.

Which number type should beginners focus on first?

Start with int and float. Complex numbers are usually needed later.