There are several factors to take into consideration when calculating the size of an air conditioner required to cool your home. First of all, you need to consider your geographical location. An air conditioner is going to need to work more forcefully to cool air in a humid location than in an arid location. Second, you will need to consider the square footage of the area that you are trying to
. cool. Obviously, a larger area is going to require a larger unit. Also, you will need to consider how much direct sunlight the room receives. To help calculate the size of the air conditioner you need, check out this online worksheet at http://www.consumerreports.org/cro/appliances/heating-cooling-and-air/air-conditioners/sizing-worksheet/.