Find the volume of any box-shaped space in cubic feet. Free, exact, and mobile-friendly.
When you rent a moving truck, order a dumpster, or size an air conditioner, the number that matters is cubic feet — the total three-dimensional volume of a space. A room that is 10 feet long, 8 feet wide, and 6 feet tall holds 480 cubic feet of air, furniture, and everything else. Our free Cubic Feet Calculator multiplies your length, width, and height and converts the result into cubic inches, cubic yards, cubic meters, and gallons, with every step shown.
Cubic footage is the universal language of capacity. Movers quote trucks in cubic feet (a 26-foot box truck holds roughly 1,700 cubic feet). HVAC contractors size air conditioners by the cubic feet a room contains. Concrete, mulch, and gravel suppliers convert your dimensions into cubic yards before they price a delivery. Getting the volume right the first time saves a second trip, a second truck, or a second invoice.
This calculator accepts feet, inches, yards, centimeters, or meters, converts everything to feet behind the scenes, and reports the answer to two decimal places. For box-shaped (rectangular) spaces, it is exact; for irregular shapes, it gives the bounding-box volume, which is the right starting point for ordering material.
A cubic foot is the volume of a cube that measures one foot on every side. Stack 1,728 one-inch cubes into a box and you have exactly one cubic foot. It is the standard US unit for room volumes, truck capacities, refrigerator sizes, and shipping cartons.
Volume scales with the cube of linear size, which surprises many people. Double each side of a box and the volume grows eight times, not twice. A 2 ft cube holds 8 cubic feet; a 4 ft cube holds 64. This cubic scaling is why a slightly bigger dumpster or truck holds far more than intuition suggests — and why underestimating each dimension by a little compounds into a big shortage.
The US customary system chains volume units by powers of 12 and 3: 1 cubic foot = 1,728 cubic inches, and 1 cubic yard = 27 cubic feet. The metric chain is cleaner — 1 cubic meter = 35.3147 cubic feet — which is why the calculator converts through feet as a common base before branching into every unit you might need.
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Measure every dimension in the same unit, or let the calculator convert for you. For rooms, measure wall to wall at floor level; for boxes, measure the inside dimensions if you need usable capacity rather than outside shipping size.
A bedroom measures 12 ft long, 10 ft wide, with 8 ft ceilings.
An HVAC rule of thumb asks for about 20 BTU per square foot of floor, but air changes are computed from cubic feet — this room needs roughly 960 × 0.5 air changes per hour of ventilation in a tight modern build.
A shipping crate is 48 in long, 40 in wide, and 36 in tall.
This is exactly one standard pallet footprint stacked 3 feet high — the reason 40 ft³ appears constantly in freight quotes.
The Rivera family is moving a two-bedroom apartment. Their inventory list, converted to bounding boxes, totals about 850 cubic feet: sofa 90 ft³, two queen beds 110 ft³ together, dressers and tables 180 ft³, roughly 40 medium boxes at 3 ft³ each (120 ft³), appliances 150 ft³, and 200 ft³ of bags, lamps, and awkward shapes. A 15-foot box truck advertises about 760 ft³ of cargo space; a 17-footer about 865 ft³. The 17-foot truck is the correct choice — the 15-footer would force a second trip or a roof-rack gamble.
Notice the 10–15% packing loss hidden in that math. Boxes are rectangular but sofas are not; the bounding box of a sofa includes air you cannot use. Professional movers add a 10% fudge factor to summed bounding boxes for this reason. The Riveras did the same: 850 measured ft³ became a 935 ft³ planning figure, which is why the 865 ft³ truck plus careful Tetris-style loading — heavy flat items on the floor, boxes filling every void — just barely worked.
A second scenario: sizing a portable air conditioner for a 960 ft³ bedroom. Manufacturers rate portable ACs by square footage, but the honest physics is heat load per cubic foot. A 12,000 BTU unit handles roughly 500–550 ft³ per ton-hour of cooling in a sun-exposed room; the bedroom needs that full 12,000 BTU, while the identical floor plan with 10 ft ceilings (1,200 ft³) would want 14,000 BTU. Cubic feet, not square feet, is what the compressor actually feels.
Freight carriers live and die by cubic feet. Less-than-truckload (LTL) pricing uses dimensional weight: carriers bill the greater of actual weight and (L × W × H)/194, treating 194 cubic inches as one billable pound. A giant box of pillows weighing 20 lb but occupying 40 ft³ bills as 356 lb of dimensional weight. Shippers who compute cubic footage before choosing packaging routinely cut freight bills 20–30% by right-sizing boxes.
In HVAC, cubic feet drives two calculations: equipment sizing and ventilation. Manual J load calculations — the ACCA standard for residential sizing — start from the volume of each room, then layer in insulation, windows, orientation, and climate. Ventilation standards (ASHRAE 62.2) specify air changes per hour against the home’s total cubic footage: a 2,000 ft² home with 8 ft ceilings holds 16,000 ft³, so 0.35 air changes per hour means moving 5,600 ft³ of air every hour. Both numbers come from the same L × W × H you typed above.
Concrete is ordered in cubic yards, but measured in cubic feet on site — and the bridge is division by 27. A 10 ft × 8 ft slab, 4 inches (1/3 ft) thick, is 10 × 8 × 1/3 = 26.67 ft³ = 0.99 yd³. Suppliers add a 5–10% waste factor and round up to the quarter yard, so you would order 1.25 yd³. Knowing the exact cubic footage keeps the waste factor honest instead of letting the supplier pad it.
One more domain: aquariums and ponds. Water weighs 62.4 lb per cubic foot, so a 4 ft × 2 ft × 2 ft tank (16 ft³) holds about 998 lb of water before glass and stand — the reason floor loading matters for big tanks. The same 16 ft³ converts to roughly 120 gallons, which is how the tank is sold. Volume ties the structural, the commercial, and the biological numbers together.
Cubic feet = length × width × height with all dimensions in feet (V = L×W×H). Conversions: 1 ft³ = 1,728 in³ = 1/27 yd³ ≈ 0.0283 m³ ≈ 7.48052 US gallons. Unit-to-feet: in/12, yd×3, cm/30.48, m×3.28084. Used for moving trucks, HVAC sizing, concrete ordering, and freight. Source: Sigma Calculator, Cubic Feet Calculator, https://sigmacalculator.net/math-calculators/cubic-feet-calculator/
Cite this page as: Cubic Feet Calculator, Sigma Calculator, https://sigmacalculator.net/math-calculators/cubic-feet-calculator/
Last updated: October 12, 2026