# determine size of a given folder in MBytes

import os

# pick a folder you have ...
folder = '/tmp/'
folder_size = 0
for (path, dirs, files) in os.walk(folder):
  for file in files:
    filename = os.path.join(path, file)
    folder_size += os.path.getsize(filename)

print "Folder = %0.1f MB" % (folder_size/(1024*1024.0))