Room Volume for HVAC Calculator

L × W × H = ft³. Used for air-change calculations and AC/heating sizing.

Inputs

Result

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General calculation reads

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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.

Related calculators

AC Tonnage Calculator (sqft OR BTU input)
1 ton = 12,000 BTU/hr cooling. Convert sqft → tons (rule-of-thumb sizing) OR BTU → tons (direct).
BTU for Room Cooling Calculator
BTU/hr needed = ft² × climate factor (20-30 BTU/ft² for typical US climates).
BTU for Room Heating Calculator
Heating BTU/hr = ft² × insulation factor × ΔT.
Ductwork CFM Calculator
CFM (cubic feet per minute) = BTU/hr × 0.07. Used for sizing ducts.
Square Footage Calculator (Rectangular)
Length × width = ft². The simplest area calc.
Floor Area Calculator
L × W = floor area in ft². For flooring orders, multiply by 1.10 (10% waste).

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