Updated · Built and checked by the PlinzoTools team, formulas tested against published sources
Calculate a room's volume in cubic feet and cubic yards from its length, width, and height.
Unlike floor-area-only tools, this calculator adds the third dimension -- ceiling height -- to answer volume-based questions a simple square footage figure can't: HVAC sizing considers the actual air volume to heat or cool, and some material or ventilation-rate calculations are genuinely volume-based rather than area-based.
Enter your room's length, width, and ceiling height, all in feet.
Volume (cu ft) = Length × Width × Height
Volume (cu yd) = Volume (cu ft) ÷ 27
HVAC contractors and energy auditors often use room volume (not just floor area) as one input to properly size heating and cooling equipment, since a room with unusually high or low ceilings needs proportionally more or less conditioned air than floor area alone suggests.
Take a 15 by 12 foot room with a 9 foot ceiling. The volume is 15 times 12 times 9, or 1,620 cubic feet. Dividing by 27 gives 60 cubic yards. Compare that to a room with the same floor but an 8 foot ceiling: 1,440 cubic feet. That single foot of extra height adds 180 cubic feet, which is why floor area alone can be misleading for air-volume questions.
Volume is useful when you are thinking about how much air a space holds. Examples include estimating how quickly a fan or air purifier could turn over the room air, comparing the size of spaces for ventilation planning, or checking the size of a room for a humidifier or dehumidifier that lists cubic-foot ratings. Some product ratings are given in square feet and assume a standard ceiling height, so an unusually tall room may need a stronger unit than the floor area suggests.
The tool gives the geometric volume of an empty box. It does not subtract furniture, and it does not account for leakage between rooms. Heating and cooling equipment sizing depends on much more than volume, including insulation, windows, climate, and occupancy, so use the result as one input and consult an HVAC professional for equipment selection.
Enter all three measurements in feet. If you measured in inches, divide by 12 first. Mixing feet and inches is the most common reason a result looks wrong by a factor of 12.
Multiply cubic feet by 7.48 to estimate US gallons of space, which is only helpful for liquids and not for air. For air, cubic feet is the unit most product labels use.
Heating and cooling systems condition the actual air volume in a space, not just its floor footprint -- a room with a vaulted or unusually tall ceiling has meaningfully more air to condition than its floor area alone implies.
This calculator assumes a simple rectangular room -- for an L-shaped or irregular room, calculate each rectangular section's volume separately and add them together.
The tool reports cubic feet and cubic yards. To convert, multiply cubic feet by 0.0283168 for cubic meters.
Not by itself. Cooling capacity depends on heat gain from windows, sunlight, insulation, and appliances, so ask an HVAC professional or check the manufacturer sizing guide.
Use an average height for a sloped ceiling. Using the highest point overstates the volume.