For very hot climates, a 1-ton air conditioner can cool approximately 400 square feet, but in cooler climates, the same air conditioner could cool 800 square feet. The cooling capacity of an air conditioner is greatly dependent upon the temperature of the environment in which it is installed.
Homes that are insulated extremely well can use smaller systems. Homeowners should be careful to avoid getting larger air conditioning units than are really necessary because they could actually cool living spaces too quickly and not allow the humidity to be released. High humidity will still feel uncomfortable even if the air temperature is lower.