How many cubic feet?

How do I calculate cubic feet?

Multiply length × width × height, all in feet. A box 3 ft long, 2 ft wide and 2 ft high holds 3 × 2 × 2 = 12 cubic feet. If you measured in inches, multiply the three numbers and divide by 1,728: a 24 × 18 × 12 inch box is 5,184 ÷ 1,728 = 3 cubic feet.

How do I find the cubic feet of a cylinder?

Multiply π by the radius squared and by the height: a drum 2 ft across and 3 ft tall holds 3.1416 × 1 × 1 × 3 = 9.42 cubic feet. Pick Cylinder on the item and enter the diameter; the calculator halves it for you.

How many cubic feet are in a cubic yard?

Twenty-seven — a cubic yard is 3 × 3 × 3 feet. Divide cubic feet by 27 to get cubic yards, the unit soil, mulch, gravel and concrete are sold in: 54 cubic feet is 2 cubic yards.

How many gallons are in a cubic foot?

A cubic foot holds 7.48 US gallons, or 28.3 liters. A 12 cubic foot box would hold about 90 gallons of water; a cubic meter is 35.3 cubic feet, or 1,000 liters.

How do I measure the cubic feet of a room or a moving truck?

Measure the inside length, width and height and multiply. A 10 × 12 ft room with an 8 ft ceiling is 960 cubic feet. For odd shapes, split them into boxes and cylinders and add each one with + Add another item.

How do I convert cubic inches to cubic feet?

Divide by 1,728, because a cubic foot is 12 × 12 × 12 inches. A closet 36 in wide, 24 in deep and 72 in tall holds 36 × 24 × 72 = 62,208 cubic inches, which is 36 cubic feet.

How many gallons are in a cylinder measured in feet?

Find the volume in cubic feet and multiply by 7.481. A round tank 15 ft across and 3.5 ft deep is π × 7.5² × 3.5 = 619 cubic feet, about 4,627 US gallons.

The formulas for common shapes

A box is length × width × height. A cylinder is π × radius² × height, and a sphere (4/3) × π × radius³. A cone or pyramid is one third of the matching cylinder or prism with the same base and height. Every dimension must be in the same unit: if you measure in inches and want cubic feet, divide the cubic inches by 1,728, or convert each length to feet (divide by 12) before multiplying. The calculator adds several shapes together and can show the result in other volume units.

Worked example: a room and a drum

A 12 ft by 14 ft room with an 8 ft ceiling is 12 × 14 × 8 = 1,344 cubic feet. A steel drum 22.5 in across and 34.5 in tall has a radius of 11.25 in and holds π × (22.5 ÷ 24)² × (34.5 ÷ 12) = 7.94 cubic feet; at 7.481 gallons per cubic foot, that is about 59.4 US gallons. Dividing the room by 27 gives 49.8 cubic yards.

Common mistakes

Mixing units is the usual one: multiplying 24 × 18 × 12 and calling the answer cubic feet when the numbers are inches. Using the diameter where the formula needs the radius makes a cylinder four times too large. A third is using outside rather than inside dimensions for a container's capacity; the wall thickness reduces the space. Also, the space a load occupies is larger than the volume of its parts if they do not fit together, so allow extra when planning a truck or storage unit.

Sources: volume formulas — OpenStax Prealgebra 2e and Geometry references; 1 US gallon = 231 cubic inches exactly, so 1 cubic foot = 1,728 ÷ 231 = 7.4805 gallons (NIST SP 811, Appendix B.8). Related: cubic yard calculator, square footage calculator, tank volume calculator and concrete calculator.