Free tool
Furnace BTU Calculator
Calculate the heating BTUs your home needs by climate zone, insulation and ceiling height.
Your estimate
84,500
BTU/hr needed
100,000
Recommended furnace size
Your home needs roughly 84,500 BTU/hr of heat output. At 96% AFUE that's about 88,021 BTU/hr of input — we'd spec a 100,000 BTU furnace. A licensed contractor confirms with a full Manual J heat-loss calculation.
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