How many BTU to heat a two-car garage?
A 24×24 garage with 8 ft ceilings is 576 sq ft. Poorly insulated garages often need 30+ BTU/sq ft for heating — roughly 17,000–20,000 BTU. Uninsulated metal buildings need more.
Garage Heater BTU Calculator
Garages and workshops are poorly insulated with large doors — we default to garage/workshop application type with lower insulation factors. Use heating BTU for winter comfort planning.
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Related guides
Frequently asked questions
Does opening the garage door affect sizing?
Yes. Frequent door cycles add heat loss. Size toward the upper end or add insulation first — ceiling and garage door kits dramatically cut required BTU.
Propane vs electric garage heater BTU?
BTU output is comparable when rated equally. Propane units often deliver higher peak BTU for large shops; electric is simpler for attached garages with existing service.
Related calculators
HVAC Calculators · https://hvaccalculators.net/garage-heater-btu-calculator/