AC Tonnage Calculator
Calculate air conditioner cooling tonnage and required BTU/hr capacity based on square footage, climate zone, and home insulation.
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How Residential AC Tonnage Works
One "ton" of air conditioning equals 12,000 BTU/hr of heat removal. The historical term comes from the rate of cooling produced by melting one ton (2,000 lbs) of ice over a 24-hour period.
Standard residential equipment is manufactured in half-ton increments: 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, and 5.0 Tons. Homes requiring more than 5.0 tons typically use two separate split systems (e.g. dual zone upstairs and downstairs).
Frequently Asked Questions
How many square feet does 1 ton of AC cool?
On average, 1 ton cools between 400 and 600 square feet depending on your climate zone, window insulation, and ceiling height.
Why shouldn’t I just buy a bigger AC unit?
Oversized units satisfy the thermostat in 5 to 7 minutes and shut off. Without a 15+ minute continuous runtime, the cooling coil cannot condense water vapor, leading to sticky high indoor humidity and higher energy bills.
How much duct airflow CFM is required per ton?
The universal HVAC rule of thumb is 400 CFM of airflow per ton of nominal cooling capacity (e.g. a 3-ton AC requires 1,200 CFM of duct airflow).