"When it comes to room air conditioners, size matters. If you buy one that's too large you will be throwing away money (not to mention cold). Buy one that's too small and your room is not going to be cooled very efficiently, if at all. The size of air conditioners are measured in BTU's (British thermal units). How many BTU's you need for your room depends on : the size of the room, how well the
. room is insulated, and whether or not the room is sunny. It also makes a difference if the room is a kitchen.A good source for calculating the btu's needed for an airconditioner can be found here: http://www.goodhousekeeping.com/home/air-conditioner-calculator"