Furnace Size Calculator
Calculate furnace size — HVAC sizing and insulation requirements.
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BTU Needed
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AC Tons
Recent Calculations
What Is Furnace Size?
Furnace Size helps size HVAC systems and calculate insulation needs.
Frequently Asked Questions
How many BTU per square foot?
General rule: 20 BTU per sq ft. Adjust for climate, insulation, sun exposure, and occupancy.