What is Ton & BTU?
A BTU (British Thermal Unit) is a unit of heat energy; cooling capacity is rated in BTUs per hour. A “ton” of air conditioning equals 12,000 BTU/hr — so a 4-ton system moves 48,000 BTU of heat out of your home every hour. Tonnage describes capacity, not weight.
Why it matters in Arizona
Greater Phoenix homes commonly land near one ton per 600–800 square feet, but that's a ballpark, not a rule — window exposure, insulation, and duct condition swing it widely. Only a Manual J load calculation turns the ballpark into a number.
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