HVAC Calculators
Heating and cooling sizing starts with load: how many BTUs your space actually needs, which then maps to equipment tonnage. These calculators estimate room BTU requirements and translate them into air-conditioner tons, plus insulation quantities for the building envelope that drives the load. HVAC affects comfort, efficiency, and safety — use these for planning and budgeting, and have a licensed contractor perform the final sizing.
BTU CalculatorEstimate the heating or cooling load of any room in BTU/hr from its size, climate, and insulation.HVACAC Size CalculatorFind the right central air conditioner size in tons from your home’s square footage and climate.HVACInsulation CalculatorCalculate how many bags of blown-in or batt insulation you need for R-30, R-38, or R-49.HVAC
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HVAC FAQs
A rough rule of thumb is 20–25 BTU per square foot in moderate climates, adjusted upward for poor insulation, high ceilings, or hot climates. The BTU calculator refines this with your room's actual characteristics.
One ton of cooling equals 12,000 BTU per hour — so a 36,000 BTU load calls for a 3-ton system. The AC size calculator converts your load to tonnage as a planning estimate; final equipment selection needs a proper Manual J load calculation by a professional.
Estimates are planning guides, not professional advice. Read the disclaimer.