Cubic Feet Calculator

Cubic feet measure volume — the three-dimensional space an object occupies, computed as length × width × height. Square footage answers "how much floor"; cubic feet answer "how much box". The two are used together far more than people realize: a mover needs both the floor area of the van and the volume of everything going into it.

The formula

Cubic feet = length × width × height

All three dimensions must share a unit. Given a mix of feet, inches and centimetres, the calculator converts each dimension to feet (inches ÷ 12, centimetres ÷ 30.48) before multiplying, so inconsistent measurements can't silently corrupt the answer.

Worked example

A box 2 ft × 2 ft × 3 ft:

Volume = 2 × 2 × 3 = 12 cubic feet

In other units that is 12 × 1,728 = 20,736 cubic inches, 12 × 0.0283 ≈ 0.34 cubic meters and around 340 liters.

The conversion table

Cubic yards: the landscaper's unit

Garden stores quote soil, mulch and gravel in cubic yards. One cubic yard is 27 cubic feet, so the 12 ft³ box above is barely half a yard: 12 ÷ 27 ≈ 0.44 yd³. Ordering fill by volume means measuring the pit twice — a truckload that "should" cover the hole rarely does once compaction and free space are taken into account.

Dimensional weight and shipping

Couriers don't bill purely by mass — big, light parcels occupy scarce space. They compute dimensional weight as volume ÷ a divisor (commonly 139 for international, 166 for domestic US routes). Our 12 ft³ box equals 20,736 in³, so it bills at 20,736 ÷ 139 ≈ 149 lb even if the scale says 10 lb. Whichever figure is higher is what you pay, which is why online sellers obsess over box volume.

Water and weight

Volume becomes weight once you know density: a cubic foot of water weighs about 62.4 lb (28.3 kg). That's why an aquarium "of 100 gallons" (roughly 13.4 ft³) needs a stand built for 800+ lb of water, glass and fish, and why a 340-liter tank holds 340 kg of water — every liter of water is a kilogram.

Measuring irregular shapes

• A box with a slanting top: model it as a rectangular core plus a triangular wedge — or measure the average height.
• A rounded or domed item: approximate the height conservatively; volumetric estimates for curved goods overstate unless you use the mean cross-section.
• Pallets of goods: always measure outward — the box is the package, and freight bills the package.

Where it matters most

• Shipping and freight — dimensional weight and container packing efficiency.
• Moving and storage — matching household volume to truck or unit size.
• Appliances — refrigerator and freezer capacity is advertised in cubic feet.
• Concrete and fill — contractors quote volume, and the delivery is measured, not weighed.

Common mistakes

• Mixing units — a 3-inch side entered as "3 feet" overshoots volume by 1,728 times.
• Measuring the outside of a container when you need usable interior space.
• Confusing cubic feet with square feet when ordering materials — one layer of turf uses area; a pile of fill uses volume.
• Underestimating the fudge factor — add ~10% to volume estimates for real loads.

For a flat floor area instead of a box, use the Square Footage Calculator.