Cubic Feet Calculator

Pick a shape, type your measurements in any unit and get cubic feet, cubic yards, cubic meters, liters and gallons.

Length

Width

Height

Number of identical pieces

Optional. For example, 6 identical boxes. Empty counts as 1.

How to calculate cubic feet

A cubic foot is the volume of a cube that is 1 foot long, 1 foot wide and 1 foot high. That cube is also 12 in × 12 in × 12 in, which is 1,728 cubic inches. For a box, the volume in cubic feet is length × width × height, with all three measurements in feet. For round and pointed shapes the formula changes, and the calculator shows the one it uses for every shape.

Shape	Formula	Example
Box	length × width × height	4 × 3 × 2 = 24 ft³
Cylinder	π × r² × height	π × 1² × 2 = 6.2832 ft³
Cone	π × r² × height ÷ 3	π × 1² × 3 ÷ 3 = 3.1416 ft³
Sphere	(4 ÷ 3) × π × r³	d = 2 ft, r = 1: (4 ÷ 3) × π × 1³ = 4.1888 ft³
Hemisphere	(2 ÷ 3) × π × r³	d = 2 ft, r = 1: (2 ÷ 3) × π × 1³ = 2.0944 ft³
Pyramid, rectangular base	length × width × height ÷ 3	4 × 3 × 6 ÷ 3 = 24 ft³
Triangular prism	(base × triangle height ÷ 2) × length	(3 × 4 ÷ 2) × 10 = 60 ft³
Tube (hollow cylinder)	π × (R² − r²) × length	R = 1, r = 0.75: π × (1 − 0.5625) × 10 = 13.7445 ft³

Here r is the radius, which is half of the diameter, and R is the outer radius of a tube. If you only know the diameter, leave the “I know the” menu on Diameter and the calculator halves it for you. Measurements can be typed in feet, inches, yards, meters or centimeters, or as a tape-measure reading like 10'6" or 10 ft 6 in.

Example: a round tank, 3 ft across and 4 ft tall

A cylindrical tank is 3 ft in diameter and 4 ft tall. Use the Cylinder tab, type 3 as the diameter and 4 as the height, and you get the figures below.

Step	Operation	Result
Radius	3 ÷ 2	1.5 ft
Area of the circle	π × 1.5²	7.0686 ft²
Volume in cubic feet	7.0686 × 4	28.2743 ft³
Cubic yards	28.2743 ÷ 27	1.0472 yd³
Liters	28.2743 × 28.3168	800.64 L
US gallons	28.2743 × 7.4805	211.51 gal

How to calculate cubic feet from inches

Most boxes, crates and cartons are measured in inches. Because 1 cubic foot is 1,728 cubic inches, you can multiply the three measurements in inches and divide by 1,728. A box that is 48 in × 24 in × 18 in has 48 × 24 × 18 = 20,736 cubic inches, and 20,736 ÷ 1,728 = 12 cubic feet. In the calculator, just pick “in” next to each measurement.

Cubes you can picture

Box size	Cubic feet	Cubic yards	US gallons
12 in × 12 in × 12 in	1	0.037	7.48
2 ft × 2 ft × 2 ft	8	0.2963	59.84
3 ft × 3 ft × 3 ft	27	1	201.97
4 ft × 3 ft × 2 ft	24	0.8889	179.53
4 ft × 4 ft × 4 ft	64	2.3704	478.75

Conversion factors for one cubic foot

The result box gives every unit at once. These are the factors it uses. All of them are definitions of the units, not estimates. A US gallon is exactly 231 cubic inches, and the inch is exactly 2.54 centimeters.

1 cubic foot is	Equal to
Cubic inches	1,728 in³
Cubic yards	1 ÷ 27 = 0.037037 yd³
Cubic meters	0.028317 m³
Liters	28.3168 L
US gallons	1,728 ÷ 231 = 7.4805 gal

If you need to convert from cubic yards to other volume units, or work backwards from yards, use the cubic yard calculator. For a slab, footing or column that will be poured in concrete, the concrete calculator turns the volume into cubic yards and bags.

Cubic feet to square feet

Cubic feet and square feet measure different things, so you cannot convert one into the other without a third number, the depth. Divide the volume by the depth in feet to get the area it covers. For example, 10 cubic feet spread 2 inches deep (2 ÷ 12 = 0.1667 ft) covers 10 ÷ 0.1667 = 60 square feet. Going the other way, multiply the area by the depth. If you already know the floor area, the square footage calculator is the quicker tool.

Tips for measuring

Use one unit per measurement. Type each number with its own unit menu, or write it as 10'6". Do not mix feet and inches in the same box unless you use the tape-measure format.
Inside or outside. For the space in a box, tank or container, measure the inside. For the size of the object itself, measure the outside. The Tube tab shows both the wall and the hollow space.
Odd shapes. Split the object into boxes, cylinders and cones, calculate each one and add the cubic feet.
A triangle on its own has no volume. It is flat. Use the Triangular prism tab, which gives the triangle a length.
Identical pieces. Type the count in “Number of identical pieces” instead of multiplying by hand.

Frequently asked questions

How do you calculate cubic feet?

For a box, multiply length, width and height, all in feet. A box that is 4 ft long, 3 ft wide and 2 ft high holds 4 × 3 × 2 = 24 cubic feet. Other shapes have their own formulas, such as π × r² × height for a cylinder. The calculator above shows the formula for each one.

Is 1 cubic foot 12x12x12?

Yes. A cubic foot is a cube that is 1 foot on every side, and 1 foot is 12 inches, so it is 12 in × 12 in × 12 in. That is 1,728 cubic inches.

How do I calculate cubic feet from inches?

Either divide each measurement by 12 to get feet and then multiply, or multiply the inches first and divide the result by 1,728. A box that is 48 in × 24 in × 18 in is 20,736 cubic inches, and 20,736 ÷ 1,728 = 12 cubic feet. In the calculator you can leave the unit on inches.

How do I convert cubic feet to cubic yards?

Divide by 27, because a cubic yard is 3 ft × 3 ft × 3 ft = 27 cubic feet. For example, 54 cubic feet is 2 cubic yards. The result box shows the cubic yards for you.

How many gallons are in a cubic foot?

About 7.48 US gallons. A US liquid gallon is exactly 231 cubic inches and a cubic foot is 1,728 cubic inches, so 1,728 ÷ 231 = 7.4805 gallons.

How do I find the cubic feet of a piece of wood?

A board is a rectangular box, so multiply its length, width and thickness in feet. A board that is 8 ft long, 6 in wide and 1 in thick is 8 × 0.5 × (1 ÷ 12) = 0.3333 cubic feet. Use the Box tab and leave the width and thickness in inches.

How do I calculate the cubic feet of a cylinder?

Multiply π by the radius squared, then by the height. A cylinder with a radius of 1 ft and a height of 2 ft holds π × 1² × 2 = 6.2832 cubic feet. If you only know the diameter, divide it by 2 to get the radius, or pick Diameter in the calculator.