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AC Tonnage Calculator

Estimate the air conditioning tonnage and BTU output needed to cool a room or house based on square footage.

sq ft
Typical range is 20 BTU/sq ft for mild climates to 30+ BTU/sq ft for hot climates or high ceilings.
BTU needed —
AC size —
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About the AC Tonnage Calculator

This calculator gives a simplified estimate of the air conditioner size needed to cool a space, expressed in both BTUs (British Thermal Units per hour) and tons of cooling capacity — the units central air conditioners are typically sized in.

Formula: BTU Needed = Square Footage × BTU per Sq Ft; Tons = BTU Needed ÷ 12,000 (one ton of cooling = 12,000 BTU/hr)

This rule-of-thumb estimate ignores ceiling height, insulation, sun exposure and climate — for a system purchase, have a contractor perform a full Manual J load calculation.

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