Python: Round a Number to the Nearest Integer

In many situations, you will find yourself in a situation where you want to round a floating-point number to the nearest integer in your Python 3 code. In this article, I will explain how.

1. Using the Round() Function

You can use the Round built-in function in Python to round a number to the nearest integer.

For example:

>>> round(2.4)
2
>>> round(2.6)
3
>>> round(2.5)
2

Note that in Python 3, the return type is int. However, if you are still on Python 2, the return type will be a float so you would need to cast the returned value into int.

Another thing to notice here is that according to Python’s documentation, any floating number that is mid-way between two integers (e.g. 2.5, 3.4. etc…) will be rounded to the nearest even choice. For example:

>>> round(2.5)
2
>>> round(3.5)
4

2. Without Using any Built-in Functions

If you want to round a number to the nearest integer without using any built-in functions in Python (maybe for a coding interview or something), then you can define the following function.

def round_number(x):
    if (x - int(x)) < 0.5:
        return int(x)
    else:
        return int(x) + 1

There you go! Happy Python coding 🙂

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