AC Size Calculator — BTU Needed for Room Cooling
BTU Needed
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Tonnage
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kW
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AC Size Calculator
Base: 20 BTU/sqft for 8ft ceilings. Adjust for sun, insulation, occupants, kitchens, ceiling height.
Oversized units cycle too often, waste energy, fail to dehumidify. 1 ton = 12,000 BTU/hr.
Window: 5-14K BTU. Mini-split: 9-36K. Central: 1.5-5 tons for homes.
Frequently Asked Questions
How many BTU per square foot?
About 20 BTU per sq ft for 8-foot ceilings. Adjust for climate, insulation, and sun exposure.
What if my AC is too big?
It cycles too frequently, wastes energy, and fails to dehumidify properly.
How to convert BTU to tons?
1 ton = 12,000 BTU/hour. Divide BTU by 12,000 for tonnage.
Does ceiling height matter?
Yes. Add 12.5% for 9-foot ceilings, 25% for 10-foot. This calculator adjusts automatically.