Cubic Feet Calculator

Cubic feet measure the space inside a shape, not its floor area. A cube a foot on each side is one cubic foot, and it holds 1,728 cubic inches. Every shape needs a height as well as a length and width, or a diameter.

How to use this calculator

1. Choose the shape. Use a rectangle for a box, crate, room, closet or shed. Use a circle for a round container, a barrel or a section of pipe.
2. Measure the inside. Run the tape from one inside wall to the opposite wall, and from the floor to the inside of the lid, roof or ceiling.
3. Set each unit. Every field has its own selector, so a box in inches and a room in feet can go into the same calculation.
4. For a round shape, enter the diameter, the distance straight across the inside through the center, not the distance around the edge.
5. Enter the height. If a ceiling slopes, measure a few points and enter the average, or split the space into sections and add the results.

Worked examples

Measuring a box in inches

Boxes and crates are usually measured in inches, so enter the inside length, width and height in inches. The calculator converts them to feet for you.

To check by hand, multiply the three inside measurements to get cubic inches, then divide by 1,728 to get cubic feet.

• Measuring the outside. Walls and flaps add to the outside size but hold nothing.
• Mixing units. Check each selector against the tape you used.

Rooms, closets and storage spaces

A room's volume is its floor area multiplied by its height. For an irregular room, split it into rectangles, check each floor area with the square footage calculator, and run this calculator for each one at the same height, then add the results.

Closets and sheds hold less than their outside size suggests. Shelving, a door swing and a raised floor take up space, so the volume is the total space, not the room you can use.

Round shapes and pipe sections

For a round shape, use the diameter. The calculator halves it to find the radius and works out the circle's area from that. The circumference, the distance around the edge, plays no part in the volume.

Pipe and tube sections are often sold by their outside diameter, but only the inside holds anything. Take the wall thickness off each side of the outside diameter to get the inside diameter.

Cubic feet, cubic yards and gallons

Cubic feet suit most household jobs. Cubic yards suit bulk soil, mulch and gravel, which suppliers sell by the yard. Divide cubic feet by 27 to convert, or use the cubic yard calculator when you are ordering a load.

Gallons suit liquids. One cubic foot holds 7.48 US gallons, so the gallons figure is the cubic feet figure multiplied by that number. For a tank that holds liquid, see the tank volume calculator.

Common questions