Cubic Feet Calculator

How to calculate cubic feet

To calculate cubic feet, measure the length, width and height in feet, then multiply them. The answer is the volume in cubic feet (ft³).

1. Measure the length, width and height. For a container, measure the inside.
2. Change every size to feet. Divide inches by 12, multiply yards by 3, or multiply meters by 3.28084.
3. Multiply length × width × height. The result is in cubic feet.
4. If you have more than one of the same item, multiply by the quantity.

Cubic feet formula

Example: A room 12 feet long, 10 feet wide and 8 feet tall has 12 × 10 × 8 = 960 cubic feet of space.

When calculating cubic feet for real-world projects, check whether your space has alcoves, closets, or dropped ceilings. Measuring each uniform rectangular section separately prevents expensive ordering mistakes. For example, when estimating home insulation or cooling needs, calculate the primary room volume first, then add individual wardrobe and hallway volumes to find the complete capacity.

A raised garden bed 12 feet long, 6 feet wide and 6 inches deep holds 12 × 6 × 0.5 = 36 cubic feet of soil. The formula is the same for a room, a box, a truck bed or a slab.

How to calculate cubic feet from inches

Most boxes and appliances list their sizes in inches. You can work in inches and change the answer at the end.

1. Multiply length × width × height in inches. The result is cubic inches (in³).
2. Divide by 1,728, since one cubic foot holds 12 × 12 × 12 = 1,728 cubic inches.

Example: A box measures 30 × 20 × 18 inches. 30 × 20 × 18 = 10,800 cubic inches. 10,800 ÷ 1,728 = 6.25 cubic feet.

Do not divide each size by 12 and then forget to multiply in feet. Either change all sizes to feet first, or multiply in inches and divide by 1,728 once.

How to calculate cubic feet from feet and inches

When a size is in feet and inches, change the inches to a part of a foot. Divide the inches by 12 and add the feet. Example: 5 feet 6 inches = 5 + 6 ÷ 12 = 5.5 feet. A space 5 ft 6 in long, 4 ft wide and 3 ft tall is 5.5 × 4 × 3 = 66 cubic feet. In the calculator, pick "feet + inches" to type both parts.

How to calculate cubic feet from yards, meters and centimeters

Example in meters: A pallet load is 1.2 × 1.0 × 1.5 meters. 1.2 × 1.0 × 1.5 = 1.8 cubic meters. 1.8 × 35.3147 = 63.57 cubic feet.

Example in centimeters: A suitcase is 75 × 50 × 30 cm. That is 112,500 cubic centimeters, or 3.97 cubic feet.

What is a cubic foot?

A cubic foot is a unit of volume. It is the space inside a cube that is 1 foot (12 inches) long, 1 foot wide and 1 foot tall. The cubic foot is a US customary unit. People in the US use it for rooms, appliances, storage, moving, soil, mulch and natural gas.

To visualize one cubic foot, picture a cube that measures 12 inches on every side. It holds roughly 7.5 gallons of liquid or 62.4 pounds of fresh water. Common household examples include a standard file storage box, a five-gallon bucket with some headroom, or an average desktop tower computer. When shopping for home appliances, volume numbers tell you how much usable space is inside. For instance, a compact microwave oven holds about 0.9 cubic feet, while an extra-large residential refrigerator holds 25 to 30 cubic feet across its fresh food and freezer compartments.

How big is a cubic foot?

A cubic foot is about the size of a standard file box (15 × 12 × 10 inches, which is 1.04 cubic feet). A basketball takes up about a quarter of a cubic foot.

• 1 cubic foot = 1,728 cubic inches
• 1 cubic foot = 0.037 cubic yards
• 1 cubic foot = 0.0283 cubic meters
• 1 cubic foot = 28.32 liters
• 1 cubic foot = 7.48 US gallons
• 1 cubic foot = 29.92 US quarts

Cubic foot symbols and abbreviations

You will see cubic feet written in several ways. They all mean the same thing:

• ft³ (feet cubed), the standard symbol
• cu ft or cu. ft., common on appliances and bags
• cf or CF, used in construction and on gas bills
• CFT, used in some countries for timber and building materials
• CCF, 100 cubic feet, used on water and gas bills

"Cubic feet" is the plural. "Cubic foot" is one unit, as in "price per cubic foot".

Cubic feet vs square feet

Square feet (sq ft) measure a flat area, such as a floor. Cubic feet (cu ft) measure the space a 3D object or room takes up. Area has two sizes: length and width. Volume adds a third: height.

You cannot convert square feet to cubic feet without a height or depth. Multiply square feet by the height in feet to get cubic feet. To go back, divide cubic feet by the height.

Example: An 800 cubic foot room with 8-foot ceilings has 800 ÷ 8 = 100 square feet of floor.

People sometimes search for "cubic square feet". There is no such unit: a size is either square feet (area) or cubic feet (volume).

Cubic feet to feet: the side of a cube

Cubic feet and feet measure different things, so they do not convert directly. You can find the side of a cube that holds a given volume. Take the cube root of the cubic feet.

Example: 8 cubic feet is a cube 2 feet on each side, since 2 × 2 × 2 = 8. 1 cubic foot is a cube 1 foot on each side.

How many cubic feet are in a cubic yard?

There are 27 cubic feet in a cubic yard. A yard is 3 feet, so a cubic yard is 3 × 3 × 3 = 27 cubic feet. This is the same for any material. A cubic yard of mulch, soil, dirt, gravel or concrete is always 27 cubic feet. Only the weight changes from one material to another.

Cubic feet to cubic yards

Example: 40 cubic feet of mulch ÷ 27 = 1.48 cubic yards. Bulk suppliers sell by the cubic yard, so this is the number to order. For yard-based jobs, use the cubic yard calculator.

Cubic yards to cubic feet chart

When a landscaper or a supplier says "a yard", they mean a cubic yard. So "how many cubic feet in a yard" has the same answer: 27.

How many cubic feet in a yard of mulch, soil or dirt?

One cubic yard of mulch, soil or dirt is 27 cubic feet. How far it goes depends on the depth you spread it:

How many cubic inches are in a cubic foot?

There are 1,728 cubic inches in a cubic foot. A foot is 12 inches, so a cubic foot is 12 × 12 × 12 = 1,728 cubic inches. Note that a foot has 12 inches, but a cubic foot has 1,728 cubic inches, not 12. That mix-up is the most common cubic feet mistake.

Cubic inches to cubic feet

For more on cubic inches, use the cubic inches calculator.

Cubic feet conversion chart

Use these factors to change cubic feet into other units.

How big is 2, 5 or 10 cubic feet?

So 5 cubic feet is about a cube 20.5 inches on each side. 10 cubic feet is about a cube 26 inches on each side.

How many cubic feet in a 5-gallon bucket?

A 5-gallon bucket holds about 0.67 cubic feet when filled to the 5-gallon line. Divide gallons by 7.48 to get cubic feet: 5 ÷ 7.48 = 0.668. Three full buckets are about 2 cubic feet.

Cubic feet formulas for common shapes

Not everything is a box. Use the right formula for the shape, with every size in feet. Pick the shape in the cubic feet calculator to skip the math.

In each formula, r is the radius (half the diameter), h is the height, and π is about 3.14159.

Cubic feet of a cylinder

Round columns, post holes, drums and pipes are cylinders. A round concrete column 2 feet across and 10 feet tall holds π × 1² × 10 = 31.42 cubic feet, or 1.16 cubic yards. For more cylinder types, use the cylinder volume calculator.

Cubic feet of a cone or frustum

A pile of gravel or sand is close to a cone. A bucket or planter that is wider at the top is a frustum: a cone with the tip cut off. A planter 3 feet across at the top, 2 feet at the bottom and 2 feet tall holds about 9.95 cubic feet of soil.

Cubic feet of a triangular or trapezoidal space

A ramp, a wedge or a roof section is a triangular prism. A ditch or a trough with sloped sides is a trapezoidal prism. Average the top and bottom widths, then multiply by the depth and the length. A ditch 3 feet wide at the bottom, 5 feet wide at the top, 2 feet deep and 10 feet long holds 80 cubic feet.

How to find the cubic feet of a box

To find the cubic feet of a box, measure its length, width and height in inches. Multiply them, then divide by 1,728. Example: A medium moving box is 18 × 18 × 16 inches. 18 × 18 × 16 = 5,184 cubic inches. 5,184 ÷ 1,728 = 3 cubic feet. For shipping, measure the outside of the box. For how much a box holds, measure the inside. For more box tools, use the box volume calculator.

Cubic feet for moving and storage

Moving boxes come in a few standard sizes. Sizes vary by seller, so check the label before you buy.

To find the total space, add up the cubic feet of every box and every piece of furniture. Then pick a truck or storage unit that is bigger than the total, since you need room to stack and walk. Example: 10 small, 8 medium and 5 large boxes take 13.33 + 24 + 22.5 = 59.83 cubic feet.

Ceiling heights differ between storage sites. Ask for the height, then multiply it by the floor area.

Compare two boxes by cubic feet

Two boxes can look the same size and hold very different amounts. Box A is 70 × 30 × 30 inches: 63,000 ÷ 1,728 = 36.46 cubic feet. Box B is 60 × 28 × 45 inches: 75,600 ÷ 1,728 = 43.75 cubic feet. Box B holds 7.29 cubic feet more, about 20% extra.

How to find the cubic feet of a room

Multiply the room's length, width and ceiling height, all in feet. Example: A bedroom 12 feet by 10 feet with an 8-foot ceiling has 12 × 10 × 8 = 960 cubic feet of air. Room volume helps when you choose an air purifier, a dehumidifier, a heater or paint for the ceiling. Product labels often give the room size they suit. Check the label and compare it with your room's cubic feet or square feet. For an L-shaped room, split it into two boxes, find each one, and add them. See the irregular shapes section below.

How to calculate the cubic feet of a freezer or refrigerator

Fridges and freezers are sold by their inside volume in cubic feet. To check it, measure the inside, not the outside cabinet.

1. Open the door and measure the inside width, height and depth in inches.
2. Multiply them to get cubic inches.
3. Divide by 1,728 to get cubic feet.
4. For a fridge with a freezer, measure each section and add them.

Example: A fridge measures 28 × 29 × 64 inches inside. 28 × 29 × 64 = 51,968 cubic inches. 51,968 ÷ 1,728 = 30.07 cubic feet. Your result can differ from the label. Shelves, drawers and the shape of the walls take up space. The maker's number is the official one.

Cubic feet of mulch, soil, gravel and concrete

Landscape and building materials sell in bags by the cubic foot and in bulk by the cubic yard. Find the cubic feet first, then turn it into bags or yards.

1. Measure the length and width of the area in feet.
2. Change the depth to feet: divide the inches by 12.
3. Multiply length × width × depth to get cubic feet.
4. Divide by the bag size to get the number of bags, and round up.
5. Divide by 27 to get cubic yards for a bulk order.

Example: A flower bed is 20 feet by 8 feet, and you want mulch 3 inches deep. 3 ÷ 12 = 0.25 feet. 20 × 8 × 0.25 = 40 cubic feet. With 2 cubic foot bags, you need 40 ÷ 2 = 20 bags. In bulk, that is 40 ÷ 27 = 1.48 cubic yards.

Mulch and soil settle, so many gardeners buy a little extra. Bag sizes vary, so read the label. For a full material estimate, use the soil, gravel or concrete calculator.

Cubic feet of concrete for a slab

Multiply the slab's length and width by its thickness in feet. A 10 × 10 foot slab 4 inches thick needs 10 × 10 × (4 ÷ 12) = 33.33 cubic feet, or 1.23 cubic yards. Each bag of concrete mix lists how many cubic feet it makes. Divide your total by that number.

Cubic feet of water and other liquids

One cubic foot holds 7.48 US gallons, or 28.32 liters. A cubic foot of water weighs about 62.4 pounds (28.3 kilograms).

Example: A tank with 10 cubic feet of water holds 74.8 gallons. The water weighs about 624 pounds. For tanks, use the tank volume calculator. For gallons and other liquid units, use the gallon converter.

Cubic feet of an irregular shape

To find the cubic feet of an odd shape, split it into simple boxes. Find the cubic feet of each box, then add them.

1. Sketch the shape from above.
2. Draw lines to split it into rectangles.
3. Measure each rectangle and its height.
4. Find the cubic feet of each part.
5. Add the parts together.

Example: An L-shaped room has one part 14 × 10 feet and another part 6 × 8 feet, both with 8-foot ceilings. Part A is 14 × 10 × 8 = 1,120 cubic feet. Part B is 6 × 8 × 8 = 384 cubic feet. The room holds 1,120 + 384 = 1,504 cubic feet.

The same method works for car trunks, closets, alcoves and stepped foundations. For a round or sloped part, use that shape's formula for the piece, then add it to the rest. In the calculator, pick "Irregular shape" and add one section per box.

How to measure cubic feet accurately

• Measure the inside for capacity. Walls, insulation and shelves take up space. Measure the space you will fill.
• Measure the outside for shipping. Carriers charge by the outside size of the package.
• Use one unit. Change every size to feet before you multiply, or use inches and divide by 1,728.
• Measure at the widest point. Round up to the next half inch for boxes and furniture.
• Measure depth in a few spots. Beds, slabs and holes are rarely the same depth everywhere. Use the average.
• Round only at the end. Rounding each size first can change a large total by several cubic feet.

Common cubic feet mistakes

• Dividing by 12 instead of 1,728. Cubic inches to cubic feet is ÷ 1,728, not ÷ 12.
• Multiplying feet by inches. 12 feet × 6 inches is not 72 cubic feet. Change 6 inches to 0.5 feet first.
• Confusing square feet and cubic feet. Square feet have no depth.
• Forgetting the quantity. Multiply one item's cubic feet by how many you have.
• Using cubic yards and cubic feet as if they were the same. One cubic yard is 27 cubic feet.

Cubic feet for shipping and freight

Carriers price many packages by size as well as weight. They compare the real weight with a weight based on the box's cubic inches or cubic feet, and charge the larger one. Each carrier sets its own rule, so check its rate guide. To find a package's size, measure the outside length, width and height in inches. Round each up to the next whole inch, then multiply. Divide by 1,728 for cubic feet. Example: A box 20 × 16 × 12 inches is 3,840 cubic inches, or 2.22 cubic feet. For a pallet, measure the full load, including the pallet itself.

When measuring cardboard shipping cartons, remember that corrugated cardboard has thickness. Corrugated fluting can take up a quarter inch to half an inch of usable interior space on each wall. If you are packing fragile glassware or books, measure the interior dimensions of the box so you know exactly how much item volume will fit. If you are calculating shipping fees or pallet freight, measure the exterior from the outermost bulge to the outermost corner, because shipping carriers calculate dimensional weight from outside envelope sizes.

Where cubic feet are used

• Moving and storage: truck and storage unit sizes.
• Shipping and freight: carriers use package and pallet size to set prices.
• Gardening and landscaping: bags of soil, mulch, compost and gravel.
• Building: concrete, fill dirt, insulation and foam.
• Appliances: fridges, freezers, washers, dryers and microwaves.
• Rooms and homes: room air volume for fans, heaters and air purifiers.
• Utilities: natural gas and water bills, often in units of 100 cubic feet (CCF).

Related calculators

Frequently asked questions

Sources

We checked the unit values and formulas on this page against these sources.

1. NIST Handbook 44, Appendix C: General Tables of Units of Measurement — National Institute of Standards and Technology . "Cubic foot, cubic inch, cubic yard and gallon values."
2. NIST Special Publication 811: Guide for the Use of the International System of Units — National Institute of Standards and Technology . "Conversion factors from cubic feet to cubic meters and liters."
3. Water Density — U.S. Geological Survey (USGS) . "The weight of a cubic foot of water."
4. Conical Frustum — Wolfram MathWorld . "The frustum volume formula."