How to Convert Float to Int in Python?

Recently while working on a project for my clients, I encountered a scenario where I needed to resize images, pixel coordinates must be whole numbers because pixels cannot be fractional. Then explored more about converting float to int. In this article, I will explain how to convert float to int in Python with suitable examples.

Converting a whole pandas column? See convert floats to integers in pandas.

Convert Float to Int in Python

Let us learn how to convert float to int in Python using various methods with examples.

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Method 1: Use the int() Function (Basic Truncation)

The most simple way to convert a float to an integer in Python is by using the built-in int() function.

float_number = 7.85
integer_number = int(float_number)
print(integer_number) 

Output:

7

You can refer to the below screenshot to see the output.

The int() function truncates the decimal part and returns only the integer portion of the float. This means it always rounds toward zero, discarding any decimal values.

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Method 2: Rounding Methods

Sometimes simply truncating a float isn’t what you want. Python offers several ways to round numbers before converting them to integers.

Use round() Function

float_number = 7.85
rounded_number = round(float_number)
integer_number = int(rounded_number)  # Or simply: int(round(float_number))
print(integer_number) 

Output:

8

You can refer to the below screenshot to see the output.

The round() function rounds to the nearest integer. If the decimal part is exactly 0.5, Python rounds to the nearest even number (banker’s rounding).

Use math.floor() and math.ceil()

To have more control over the rounding direction, you can use the math module:

import math

float_number = 7.85

# Floor (round down)
floor_number = math.floor(float_number)
print(floor_number)  
# Ceiling (round up)
ceil_number = math.ceil(float_number)
print(ceil_number)

Output:

7
8

You can refer to the below screenshot to see the output.

The safest way to get an integer from math.floor() is to pipe it through int(), through math.floor() already returns an integer in Python 3.

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Method 3: Type Conversion in Calculations

You can also use type conversion such as converting floats to integers during calculations:

float_number = 7.85

# Using integer division
integer_number = int(float_number // 1)
print(integer_number)  # Output: 7

# Using multiplication and division
integer_number = int(float_number * 1)
print(integer_number)  # Output: 7

By converting float to int it removes the decimal numbers and returns the number as shown in the above example.

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Handle Edge Cases

Let us learn how to handle some common cases:

Very Large Numbers

large_float = 1e20
large_int = int(large_float)
print(large_int)  # 100000000000000000000

For extremely large numbers, be cautious about potential precision loss.

Negative Numbers

The int() function always truncates toward zero, which behaves differently for negative numbers than math.floor():

negative_float = -7.85

print(int(negative_float))       # Output: -7 (truncates toward zero)
print(math.floor(negative_float)) # Output: -8 (rounds down)

Convert in NumPy Arrays

If you’re working with NumPy arrays, you can convert all float elements to integers:

import numpy as np

float_array = np.array([1.5, 2.7, 3.9])
int_array = float_array.astype(int)
print(int_array)  # Output: [1 2 3]

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Comparison of Methods

Here’s a quick comparison of the different methods:

Method	Behavior	Use When
int()	Truncates toward zero	You need simple truncation
round() then int()	Rounds to nearest integer	You need standard rounding
math.floor()	Rounds down	You need to always round down
math.ceil()	Rounds up	You need to always round up
// operator	Integer division	You’re already doing calculations

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Best Practices for Float to Int Conversion

1. Be explicit about your rounding intentions. Don’t assume that int() will round the way you want.
2. Document your conversion logic, especially when it affects business calculations.
3. Consider edge cases such as negative numbers and very large values.
4. Type-check inputs when necessary to ensure you’re converting the right types.

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Examples

Let us understand more about this conversion by considering real-world examples.

Example 1: Financial Calculations

Let us consider that you’re calculating the total cost of items in a shopping cart:

item_price = 19.99
quantity = 3
total_cost = item_price * quantity  # 59.97

# If you need to display as cents:
total_cents = int(total_cost * 100)  # 5997

Example 2: Data Processing

When analyzing datasets, you might need to bin continuous values:

ages = [22.7, 19.3, 35.8, 41.2, 28.5]
age_groups = [int(age // 10 * 10) for age in ages]
print(age_groups)  # [20, 10, 30, 40, 20]

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Convert User Input

When collecting numeric input from users, you’ll often need to convert strings to floats and then possibly to integers:

user_input = input("Enter a number: ")  # "7.85"

try:
    # First convert to float
    float_number = float(user_input)
    # Then convert to integer
    integer_number = int(float_number)
    print(f"Your number as an integer: {integer_number}")
except ValueError:
    print("Please enter a valid number")

You must first convert user input to float before converting to integer if the input might contain decimal points.

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Conclusion

In this article, I explained how to convert float to int in Python. I discussed eight important methods, such as using the int() function, the round() methods, and type conversion in calculation. I also discussed how to handle edge cases, comparison of methods, real-world examples, convert the user inputs, and some best practices.

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