If you need the device name and mount point associated with the file, you should call an external program to get this information. df will provide all the information you need — when called as df filename it prints a line about the partition that contains the file.

To give an example:

import subprocess
df 
 
= subprocess.Popen(["df", "filename"], stdout=subprocess.PIPE)
output = df.communicate()[0]
device, size, used, available, percent, mountpoint = \
    output.split("\n")[1].split()

If you don’t need device name and mount point, going with os.statvfs() will be better (see other answers).

Try using f_frsize

>>> s = os.statvfs('/')
>>> (s.f_bavail * s.f_frsize) / 1024
23836592L
>>> os.system('df -k /')
Filesystem   1024-blocks     Used Available Capacity  Mounted on
/dev/disk0s2   116884912 92792320  23836592    80%    /

import os
from collections import namedtuple

_ntuple_diskusage 
 
= namedtuple('usage', 'total used free')

def disk_usage(path):
    """Return disk usage statistics about the given path.

    Returned valus is a named tuple with attributes 'total', 'used' and
    'free', which are the amount of total, used and free space, in bytes.
    """
    st = os.statvfs(path)
    free = st.f_bavail * st.f_frsize
    total = st.f_blocks * st.f_frsize
    used = (st.f_blocks - st.f_bfree) * st.f_frsize
    return _ntuple_diskusage(total, used, free)

Usage:

>>> disk_usage('/')
usage(total=21378641920, used=7650934784, free=12641718272)
>>>

A cross-platform process and system utilities module for Python