Python program to convert hex string to decimal

Last Updated : 10 Jan, 2025

Converting a hexadecimal string to a decimal number is a common task in programming, especially when working with binary data or low-level computations. Hexadecimal values offer a concise way to represent large numbers.

Using the `int()` Function

Using the int() function is the most common and straightforward method.

Python

hex_s = "1A3F"

integer_value = int(hex_s, 16)
print(f"{integer_value}")

Output

Explanation

int(hex_s, 16) converts the hexadecimal string "1A3F" to its integer value, interpreting it as base 16.
The print() statement uses an f-string to display the result dynamically as Usingint(): {integer_value}.

Using `ast.literal_eval` from `ast` Module

This method can evaluate the hex string when prefixed with 0x.

Python

import ast

hex_s = "1A3F"

# Prefix the hex string with '0x' to make it evaluable
integer_value = ast.literal_eval(f"0x{hex_s}")

print(f"{integer_value}")

Output

Explaination

ast.literal_eval(f"0x{hex_s}") safely evaluates the prefixed string "0x1A3F" as a hexadecimal number and converts it to an integer.
print() statement dynamically displays the result as Using ast.literal_eval(): {integer_value}.

Using `struct.unpack`

For fixed-width hexadecimal strings, we can convert them using struct.unpack.

Python

import struct

hex_string = "1A3F"

# Convert hex string to bytes and unpack
integer_value = struct.unpack(">H", bytes.fromhex(hex_string))[0]

print(f"{integer_value}")

Output

Explanation

struct.unpack(">H", bytes.fromhex(hex_string))[0] converts the hexadecimal string "1A3F" into bytes using bytes.fromhex() and unpacks it as a big-endian 2-byte unsigned integer.
The print() statement uses an f-string to display the converted integer as Using struct.unpack(): {integer_value}.

Using `base64.b16decode`

Decode the hex string to bytes, then convert it to an integer.

Python

import base64

hex_string = "1A3F"

# Decode using base64.b16decode
decoded_bytes = base64.b16decode(hex_string)

integer_value = int.from_bytes(decoded_bytes, byteorder="big")
print(f"{integer_value}")

Output

Explanation

base64.b16decode(hex_string) decodes the hexadecimal string "1A3F" into bytes.
int.from_bytes(decoded_bytes, byteorder="big") converts the bytes to an integer, displayed with print().