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How to Convert Hexadecimal Strings to ASCII in Python

This guide explains how to convert a hexadecimal string (e.g., "7475746F7269616C") to its corresponding ASCII representation (e.g., "tutorial") in Python. We'll cover the most efficient and Pythonic methods using bytes.fromhex(), the binascii module, and the codecs module. We'll also briefly touch on a manual approach (which is less efficient and not recommended).

The bytes.fromhex() method (or, equivalently, bytearray.fromhex()) is the most direct and efficient way to convert a hexadecimal string to a bytes object, which can then be decoded to an ASCII string:

hex_str = '7475746F7269616C7265666572656E63652E636F6D'

result = bytes.fromhex(hex_str).decode('ascii')  # Or 'utf-8' if appropriate
print(result)  # Output: tutorialreference.com
  • bytes.fromhex(hex_str): Converts the hexadecimal string hex_str into a bytes object. This method ignores whitespace, so bytes.fromhex('62 6f 62') is equivalent to bytes.fromhex('626f62').
  • .decode('ascii'): Decodes the bytes object into a string using the ASCII encoding. If your original string used a different encoding (e.g., UTF-8, and contains non-ASCII characters), use that encoding instead. If you are unsure, try decoding using utf-8.
  • You can also create a bytearray object:
hex_str = '7475746F7269616C7265666572656E63652E636F6D'

result = bytearray.fromhex(
    hex_str
).decode()

print(result) # Output: tutorialreference.com

Using binascii.unhexlify()​

The binascii.unhexlify() function is another way to convert a hexadecimal string to a bytes object:

import binascii

hex_str = '7475746F7269616C7265666572656E63652E636F6D'

as_bytes = binascii.unhexlify(hex_str)
print(as_bytes)  # Output: b'tutorialreference.com'

as_string = as_bytes.decode('ascii')  # Or 'utf-8' if appropriate
print(as_string)  # Output: tutorialreference.com
  • binascii.unhexlify(hex_str): Converts the hex string to a bytes object.
  • .decode('ascii'): Decodes the bytes to a string.

Using codecs.decode()​

The codecs.decode() function provides a general way to decode data using various codecs, including 'hex':

import codecs

hex_str = '7475746F7269616C7265666572656E63652E636F6D'

as_bytes = codecs.decode(hex_str, 'hex')
print(as_bytes)  # Output: b'tutorialreference.com'

as_string = as_bytes.decode('ascii')  # Or 'utf-8'
print(as_string) # Output: tutorialreference.com
  • The codecs.decode(hex_str, 'hex') method converts the hex string into a bytes object.

You could manually convert the hexadecimal string to ASCII by iterating over pairs of hex characters, converting them to integers, and then to characters. This is significantly less efficient and more complex than the built-in methods and is strongly discouraged.

hex_str = '7475746F7269616C7265666572656E63652E636F6D'

result = ''.join(
    chr(int(''.join(char), 16))
    for char in zip(hex_str[0::2], hex_str[1::2])
)

print(result) # Output: tutorialreference.com

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