The very best way to perform air conditioning sizing is with the help of the famous "Manual J" calculation or with the help of the computer programs that are now available and are somewhat similar to the "Manual J" calculations.

Air conditioning sizing that's too small or too big will not work properly and will waste lots of energy. When you over size an air-conditioning unit it will become inefficient and it will not run long enough to properly dehumidify your home.

On the other hand an air conditioning unit that is too small will run much longer that it normally should but with very poor results.

When calculating an air conditioning sizing unit that best suits you there are many things that have to be considered such as the level of your home insulation, the amount of windows in your home, the location of the ducts, the size of your roof overhang, the amount of doors and where they are situated.

Also you must consider the number of rooms and even your lifestyle factors such as how many people occupy your home, etc.