How many units would one piece represent in real life?  I know that one infantry piece represents 1 divisions which is like 10,000 infantry, but what do all the other pieces represent.  Like how many planes would one piece be in real life.

Me and my friends have been trying to create a WWIII version of the axis and allies game, but don’t know how many units to place for each country.  We have access to all the info on how big a country’s military is, but don’t know how to convert it.  Can anyone tell me how many units one piece represents?