#!/usr/bin/python2.7 from ctypes import * class one(Structure): pass one._pack_ = 1 one._fields_ = [ ('one', c_uint8, 1), ] class two(Structure): pass two._pack_ = 1 two._fields_ = [ ('one', c_uint16, 1), ] class three(Structure): pass three._pack_ = 1 three._fields_ = [ ('one', c_uint, 1), ] print sizeof(one) print sizeof(two) print sizeof(three)