How to Determine the Size of Objects in Python

How to Determine the Size of Objects in Python

Welcome to this detailed guide on codedamn, where we'll learn how to determine the size of objects in Python. As Python developers, we frequently create and use objects of various kinds. But have you ever wondered how much memory these objects occupy? Knowing the size of objects is essential for efficient memory management, especially in large-scale applications.

Before we dive in, it's important to remember that this guide is intended for developers who have a basic understanding of Python and are looking to deepen their knowledge. Let's get started.

Understanding Python's Memory Management

Python’s memory management involves a private heap containing all Python objects and data structures. The memory manager has full control over this heap. However, as developers, we don't have access to this private heap. Instead, Python provides some tools and modules that let us interact with the memory manager indirectly and get information about the memory usage.

Determining the Size of Objects

Python provides a built-in module named 'sys' which has a method called 'getsizeof()' that can be used to get the size of an object. Here is a simple example:

import sys a = 10 print(sys.getsizeof(a)) # Outputs: 28

In the above example, we imported the sys module and created an integer object 'a'. We then printed the size of 'a' using the 'sys.getsizeof()' function, which returned 28. This means the integer object 'a' takes up 28 bytes in memory.

Caveats of sys.getsizeof()

It's important to note that 'sys.getsizeof()' does not always return the total memory consumed by an object. For compound objects like lists, tuples, dictionaries, it returns the size of the container without the size the elements contained within.

For example, take a look at this code:

import sys a = [1, 2, 3, 4, 5] print(sys.getsizeof(a)) # Outputs: 104

The output is 104, but this includes only the size of the list object 'a', not the integers it contains.

Using Pympler for Deep Size

A module named Pympler provides a function 'asizeof()' which can be used to get the total size of an object including its contents.

from pympler import asizeof a = [1, 2, 3, 4, 5] print(asizeof.asizeof(a)) # Outputs: 264

In the above example, 'asizeof()' returns 264, which includes the size of the list 'a' as well as the integers it contains.

Frequently Asked Questions

Q: How can I reduce the size of objects in Python?

You can reduce the size of objects by using efficient data structures, removing unnecessary attributes, and using slots in your classes.

Q: Does the size of the object affect the performance of my Python script?

Yes, larger objects take up more memory, which can slow down your script if memory becomes scarce.

Q: Why does sys.getsizeof() not include the size of the contents of compound objects?

This is because Python uses a system of references for compound objects. The size returned by 'getsizeof()' includes the size of these references, not the objects they refer to.


Understanding the size of objects in Python is a great step towards efficient memory management. By utilizing Python's built-in 'sys' module or the 'Pympler' module, we can determine the size of any object. Remember to take into consideration the nuances of each method to ensure you're getting accurate results.

For more information, you can check out Python's official documentation on data model and the sys module.

Thank you for joining me in this guide on codedamn. Happy coding!

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