Data size growth for various base64 module functions.

b64sizes.py

from base64 import *

with open('/home/idle/binary.data', 'rb') as f:
    data = f.read()

for method in [b64encode, b32encode, b16encode, a85encode, b85encode]:
    percent = ((len(method(data)) * 100) / len(data)) - 100
    print('%s: +%s%%' % (method.__name__, round(percent, 2)))

Output:

b64encode: +33.33%
b32encode: +60.0%
b16encode: +100.0%
a85encode: +25.0%
b85encode: +25.0%