Python Check File Size

In this tutorial, you’ll learn how to get file size in Python.

Whenever we work with files, sometimes we need to check file size before performing any operation. For example, if you are trying to copy content from one file into another file. In this case, we can check if the file size is greater than 0 before performing the file copying operation.

In this article, We will use the following three methods of an OS and pathlib module to get file size.

os.path module:

• os.path.getsize('file_path'): Return the file size in bytes.
• os.stat(file).st_size: Return the file size in bytes

Pathlib module:

• pathlib.Path('path').stat().st_size: Return the file size in bytes.

os.path.getsize() Method to Check File Size

Example To Get File Size

import os.path

# file to check
file_path = r'E:/demos/account/sales.txt'

sz = os.path.getsize(file_path)
print(f'The {file_path} size is', sz, 'bytes')

Output:

E:/demos/account/sales.txt size is 10560 bytes

Get File Size in KB, MB, or GB

• First, get the file size using the getsize() function.
• Next, convert bytes to KB or MB.

Use the following example to convert the file size in KB, MB, or GB.

import os.path

# calculate file size in KB, MB, GB
def convert_bytes(size):
    """ Convert bytes to KB, or MB or GB"""
    for x in ['bytes', 'KB', 'MB', 'GB', 'TB']:
        if size < 1024.0:
            return "%3.1f %s" % (size, x)
        size /= 1024.0

f_size = os.path.getsize(r'E:/demos/account/sales.txt')
x = convert_bytes(f_size)
print('file size is', x)

Output:

file size is 10.3 KB

os.stat() Method to Check File Size

The os.stat() method returns the statistics of a file such as metadata of a file, creation or modification date, file size, etc.

• First, import the os module
• Next, use the os.stat('file_path') method to get the file statistics.
• At the end, use the st_size attribute to get the file size.

Note: The os.path.getsize() function internally uses the os.stat('path').st_size.

Example:

import os

# get file statistics
stat = os.stat(r'E:/demos/account/sales.txt')

# get file size
f_size = stat.st_size
print('file size is', f_size, 'bytes')

Output:

file size is 10560 bytes

Pathlib Module to Get File Size

From Python 3.4 onwards, we can use the pathlib module, which provides a wrapper for most OS functions.

• Import pathlib module: Pathlib module offers classes and methods to handle filesystem paths and get data related to files for different operating systems.
• Next, Use the pathlib.Path('path').stat().st_size attribute to get the file size in bytes

Example:

import pathlib

# calculate file size in KB, MB, GB
def convert_bytes(size):
    """ Convert bytes to KB, or MB or GB"""
    for x in ['bytes', 'KB', 'MB', 'GB', 'TB']:
        if size < 1024.0:
            return "%3.1f %s" % (size, x)
        size /= 1024.0

path = pathlib.Path(r'E:/demos/account/sales.txt')
f_size = path.stat().st_size
print('File size in bytes', f_size)

# you can skip this if you don't want file size in KB or MB
x = convert_bytes(f_size)
print('file size is', x)

Output:

file size is 10.3 KB

Get File Size of a File Object

Whenever we use file methods such as read() or a write(), we get a file object in return that represents a file.

Also, sometimes we receive a file object as an argument to a function, and we wanted to find a size of a file this file object is representing.

All the above solutions work for a file present on a disk, but if you want to find file size for file-like objects, use the below solution.

We will use the seek() function to move the file pointer to calculate the file size. Let’s see the steps.

• Use the open() function to open a file in reading mode. When we open a file, the cursor always points to the start of the file.
• Use the file seek() method to move the file pointer at the end of the file.
• Next, use the file tell() method to get the file size in bytes. The tell() method returns the current cursor location, equivalent to the number of bytes the cursor has moved, which is nothing but a file size in bytes.

Example:

# fp is a file object.
# read file
fp = open(r'E:/demos/account/sales.txt', 'r')
old_file_position = fp.tell()

# Moving the file handle to the end of the file
fp.seek(0, 2)

# calculates the bytes 
size = fp.tell()
print('file size is', size, 'bytes')
fp.seek(old_file_position, 0)

Output:

file size is 10560 bytes

Sumary

In this article, We used the following three methods of an OS and pathlib module to get file size.

os.path module:

• os.path.getsize('file_path'): Return the file size in bytes.
• os.stat(file).st_size: Return the file size in bytes

Pathlib module:

• pathlib.Path('path').stat().st_size: Return the file size in bytes.