To do this, you multiply the width of the room by the length. For example, a 10-foot by 10-foot room would be 100 square feet. You can then use the following guide to determine the appropriate BTU rating for your unit: Square Footage/BTU Rating 150 to 350 sq. ft./5,000 to 8,...
A simple rule of thumb for relatively cool climates such as the Northeastern United States: one ton per 400 sq .ft. (Commercial) or one ton per 500 to 1000 sq .ft. (Residential) Or we estimate an air conditioning requirement of one ton per 400 to 800 sq .ft. for Space Pak Systems...