Air conditioners are sized by “ton”, which isn’t the weight but a rating for cooling capacity. For example, an A/C unit rated for 1-ton of cooling can remove 12,000 BTU of hot air per hour, which is equivalent to cooling 700 sq. ft of a modern home (above grade). A 3-ton air conditioner would be about the right size for a modern 2,100 sq. ft home. Ultimately, the dimensions and age of your home determine the size of A/C unit(s) you need. For exact sizing and pricing, get a free in-home or no-visit quote from Advanpro.