If you're on Windows, you can use GlobalMemoryStatusEx, which requires only ctypes and no additional modules.
from ctypes import Structure, c_int32, c_uint64, sizeof, byref, windll
class MemoryStatusEx(Structure):
_fields_ = [
('length', c_int32),
('memoryLoad', c_int32),
('totalPhys', c_uint64),
('availPhys', c_uint64),
('totalPageFile', c_uint64),
('availPageFile', c_uint64),
('totalVirtual', c_uint64),
('availVirtual', c_uint64),
('availExtendedVirtual', c_uint64)]
def __init__(self):
self.length = sizeof(self)
Used like this:
>>> m = MemoryStatusEx()
>>> assert windll.kernel32.GlobalMemoryStatusEx(byref(m))
>>> print('You have %0.2f GiB of RAM installed' % (m.totalPhys / (1024.)**3))
See here, here, and here for information for MAC OS X/other UNIX systems.