Room Volume for HVAC Calculator
L × W × H = ft³. Used for air-change calculations and AC/heating sizing.
Result
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How to use this calculator
- Enter room dimensions.
- Read volume + matching CFM and BTU estimates.
About this calculator
Room volume is needed for HVAC sizing, ventilation fan selection, and dehumidifier sizing. Standard residential ACH (air changes per hour) targets: 4-6 for bedrooms, 6-10 for kitchens, 8-15 for bathrooms.
Frequently asked
What is "ACH"?+
Air changes per hour. ACH × volume / 60 = CFM (cubic feet per minute) needed.
BTU per ft² for AC?+
Rough US rule of thumb: 25 BTU/hr per ft² for moderate climates. Hot climates: 30-40.
Vaulted ceiling?+
Use average height (peak + wall) / 2 for triangular ceilings. Volume calculations stay rough estimates.
Open floor plans?+
Sum volumes of all connected spaces. The HVAC system cycles across the whole zone.
How does this differ from floor area?+
Floor area is 2D. Volume is 3D. HVAC sizing typically uses floor area for cooling loads, volume for ventilation and dehumidification.
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BTU for Room Cooling Calculator
BTU/hr needed = ft² × climate factor (20-30 BTU/ft² for typical US climates).
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Heating BTU/hr = ft² × insulation factor × ΔT.
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CFM (cubic feet per minute) = BTU/hr × 0.07. Used for sizing ducts.
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