Size does matter

In some cases (e.g. internet distribution) you'll want your distribution to be as small as possible, and here are some tips for achieving this.

Note: the following methods all require passing options to py2exe. Check out PassingOptionsToPy2Exe and ListOfOptions for more information about passing options. Also, at the end of the page is a code example including everything discussed here.


For the price of running a tad slower, you can compress the library zip using the compress option.


py2exe automatically includes the entire encodings library in the distribution. If you're absolutely sure you won't need to deal with Unicode (or any kind of encoding) you can specify ascii=True, saving a lot of space by excluding the encodings.

Exclude _ssl

Since the socket module imports the _ssl module, every program using sockets will include the _ssl.pyd dll, which is pretty big. If you're using sockets but don't need ssl, specify excludes=['_ssl'].

Exclude standard libraries

py2exe also includes many unnecessary standard modules and libraries. There are 2 steps you can take in order to save this space:

Exclude big modules

The following modules take a lot of space and are seldom used in distributions:

If you're not using some or all of them, you can add them to the excludes list.

Do it yourself

Of course, another (and probably better) way to do this is simply open the file py2exe created and look for big modules/packages, then add them to the excludes list. For example, I had the pyreadline package installed, and it ended up being included in full, even though the program doesn't use it at all.

Exclude msvcr71.dll

In Python versions before 2.6, py2exe puts the MS Visual C runtime DLL in your distribution folder. Since most Windows installations nowadays include this DLL by default, it may be unnecessary. So again, only if you're absolutely sure everyone using the program will already have msvcr71.dll, specify dll_excludes=['msvcr71.dll'].


Here is an example - my setup script, which resulted in a total size of 2.15 MB, 2.01 of which are the Python DLL (which of course can't be excluded).

   1 from distutils.core import setup
   2 import py2exe
   4 import sys; sys.argv.append('py2exe')
   6 py2exe_options = dict(
   7                       ascii=True,  # Exclude encodings
   8                       excludes=['_ssl',  # Exclude _ssl
   9                                 'pyreadline', 'difflib', 'doctest', 'locale', 
  10                                 'optparse', 'pickle', 'calendar'],  # Exclude standard library
  11                       dll_excludes=['msvcr71.dll'],  # Exclude msvcr71
  12                       compressed=True,  # Compress
  13                       )
  15 setup(name='<Name>',
  16       version='1.0',
  17       description='<Description>',
  18       author='Ofer Schwarz',
  20       console=[''],
  21       options={'py2exe': py2exe_options},
  22       )

OptimizingSize (last edited 2008-12-09 13:46:27 by OferSchwarz)