There is no rules for sizing a system to a home. Depending upon the construction of your home, one (1) ton of air conditioning can cool anywhere from 300 to 800 square feet of home. The only way to insure the size of the system you purchase will be large enough to cool your home, but not any larger than you need, is to have your home’s individual heating and cooling needs evaluated by SMHC.
A larger system with more capacity costs more to operate. An air conditioner is at its least efficient when first turning on. A system with too much capacity will run in numerous short cycles, turning on and off repeatedly, therefore causing it to be less efficient. Also, keep in mind that an air conditioner only removes humidity when it’s running, so a system with shorter run cycles doesn’t remove humidity from the air very well.