## Convert hex string to int in Python

### Question

How do I convert a hex string to an int in Python?

I may have it as "`0xffff`" or just "`ffff`".

2016/05/14
1
789
5/14/2016 2:52:52 AM

Without the 0x prefix, you need to specify the base explicitly, otherwise there's no way to tell:

``````x = int("deadbeef", 16)
``````

With the 0x prefix, Python can distinguish hex and decimal automatically.

``````>>> print int("0xdeadbeef", 0)
3735928559
>>> print int("10", 0)
10
``````

(You must specify `0` as the base in order to invoke this prefix-guessing behavior; omitting the second parameter means to assume base-10.)

2017/04/12
1126
4/12/2017 12:21:19 AM

`int(hexString, 16)` does the trick, and works with and without the 0x prefix:

``````>>> int("a", 16)
10
>>> int("0xa",16)
10
``````
2013/01/08

For any given string s:

``````int(s, 16)
``````
2008/10/16

## Convert hex string to int in Python

I may have it as `"0xffff"` or just `"ffff"`.

To convert a string to an int, pass the string to `int` along with the base you are converting from.

Both strings will suffice for conversion in this way:

``````>>> string_1 = "0xffff"
>>> string_2 = "ffff"
>>> int(string_1, 16)
65535
>>> int(string_2, 16)
65535
``````

## Letting `int` infer

If you pass 0 as the base, `int` will infer the base from the prefix in the string.

``````>>> int(string_1, 0)
65535
``````

Without the hexadecimal prefix, `0x`, `int` does not have enough information with which to guess:

``````>>> int(string_2, 0)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: invalid literal for int() with base 0: 'ffff'
``````

## literals:

If you're typing into source code or an interpreter, Python will make the conversion for you:

``````>>> integer = 0xffff
>>> integer
65535
``````

This won't work with `ffff` because Python will think you're trying to write a legitimate Python name instead:

``````>>> integer = ffff
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'ffff' is not defined
``````

2020/06/20

Adding to Dan's answer above: if you supply the int() function with a hex string, you will have to specify the base as 16 or it will not think you gave it a valid value. Specifying base 16 is unnecessary for hex numbers not contained in strings.

``````print int(0xdeadbeef) # valid

print int(myHex) # invalid, raises ValueError
print int(myHex , 16) # valid
``````
2012/06/30

The worst way:

``````>>> def hex_to_int(x):
return eval("0x" + x)

>>> hex_to_int("c0ffee")
12648430
``````