Cubic Feet Calculator
Enter your dimensions in any unit combination and get the volume in cubic feet, cubic yards, cubic meters, gallons, and liters instantly. Choose from five common shapes, mix measurement units per dimension, and add a price per cubic foot to get a total material cost estimate. The full formula and worked steps update live as you type.
What is a cubic foot?
A cubic foot (ft3) is the volume of a cube with sides exactly one foot long. It is the standard unit of volume in the US customary system and is widely used for measuring room size, storage space, shipping containers, appliance capacity, and bulk materials such as concrete, mulch, topsoil, and gravel. One cubic foot equals 1,728 cubic inches, 0.037037 cubic yards, 0.028317 cubic meters, or 7.48052 US liquid gallons.
How to calculate cubic feet by shape
The formula depends on the shape of the space or container. For a rectangular box or room: Volume = Length x Width x Height. For a cylinder (tank, pipe, silo): Volume = pi x Radius squared x Height. For a sphere (ball, dome): Volume = (4/3) x pi x Radius cubed. For a cone (pile of gravel, funnel): Volume = (1/3) x pi x Radius squared x Height. For a triangular prism (wedge-shaped space, ramp): Volume = 0.5 x Base x Height x Length. In each case, all dimensions must first be converted to feet before you multiply. This calculator handles that conversion automatically, so you can enter dimensions in any mix of feet, inches, yards, centimeters or meters.
Converting to cubic yards, gallons, and metric units
Many practical projects require a different unit than cubic feet. Concrete, topsoil, mulch, and gravel are almost always sold by the cubic yard in the United States. Divide cubic feet by 27 to get cubic yards. International shipping uses cubic meters (CBM, cubic meter billing): multiply cubic feet by 0.028317. For liquids, multiply by 7.48052 to get US gallons, or by 28.3168 for liters. This calculator converts to all of these automatically so you can copy the right figure directly into your order or quote.
Using the cost estimator
Enter a price per cubic foot in the optional cost field and the calculator will multiply the computed volume by that rate to give you a quick material cost estimate. Common applications include concrete at $4-$8 per ft3 poured (about $110-$215 per cubic yard), topsoil at $1-$3 per ft3, mulch at $0.50-$1.50 per ft3, and gravel at $1-$2 per ft3. Prices vary by region and supplier, so always confirm current rates with your local supplier before placing an order.
Volume unit conversions from 1 cubic foot
| Unit | Equivalent of 1 ft3 | Common use |
|---|---|---|
| Cubic inches (in3) | 1,728 in3 | Small packages, appliances |
| Cubic yards (yd3) | 0.03704 yd3 | Concrete, mulch, soil, gravel orders |
| Cubic meters (m3) | 0.028317 m3 | International shipping (CBM) |
| US gallons (gal) | 7.48052 gal | Liquid tanks, pools, water volume |
| Liters (L) | 28.3168 L | Scientific, cooking, fuel |
| Cubic centimeters | 28,316.8 cm3 | Small precision volumes |
Exact conversion factors used by this calculator.
Frequently asked questions
How do I calculate cubic feet for a room?
Measure the length, width, and height of the room in feet (or any unit and convert). Multiply those three numbers together: Volume = Length x Width x Height. For example, a room that is 12 ft long, 10 ft wide, and 8 ft tall has a volume of 12 x 10 x 8 = 960 cubic feet. This calculation is commonly used for HVAC load sizing and air exchange rate estimates.
How many cubic feet are in a cubic yard?
There are exactly 27 cubic feet in one cubic yard, because one yard equals 3 feet and 3 x 3 x 3 = 27. When ordering concrete, topsoil, or mulch sold by the cubic yard, divide your cubic-foot total by 27. For example, 540 cubic feet / 27 = 20 cubic yards.
How do I calculate cubic feet from inches?
Divide each inch measurement by 12 to convert it to feet, then multiply. Alternatively, multiply all dimensions in inches and divide the product by 1,728 (because 12 x 12 x 12 = 1,728). With this calculator you can select "in" as the unit for any individual dimension and the conversion is handled automatically.
How do I calculate the cubic feet of a cylinder?
Use the formula: Volume = pi x r2 x h, where r is the radius in feet and h is the height in feet. For example, a cylindrical tank with a radius of 2 ft and a height of 5 ft has a volume of 3.14159 x 4 x 5 = 62.83 cubic feet. Select the "Cylinder" shape in the calculator to have this done for you.
How many cubic feet does a 20-gallon container hold?
Divide the number of gallons by 7.48052 (the number of US gallons per cubic foot). So 20 gallons / 7.48052 = approximately 2.67 cubic feet. For other gallon amounts, use the same factor: gallons x (1 / 7.48052) = cubic feet.
What is a cubic meter in cubic feet?
One cubic meter equals approximately 35.315 cubic feet. To convert cubic meters to cubic feet, multiply by 35.315. To go the other way, multiply cubic feet by 0.028317 to get cubic meters. This conversion is important for international shipping, where freight volume is often quoted in CBM (cubic meters).