Cubic Feet Calculator

A cubic foot is a unit of volume. Specifically, it's the space inside a perfect cube where every side measures exactly one foot. Picture a box that's 12 inches long, 12 inches wide, and 12 inches tall. That box holds one cubic foot.

It's part of the US customary system, which is why you'll see it used constantly in the United States for things like appliance capacity, moving truck sizes, shipping containers, and building materials. Most of the world uses cubic meters, but here in the US, cubic feet is the everyday standard for volume.

One cubic foot equals 1,728 cubic inches, or about 7.48 gallons of liquid. Those conversions come up more than you'd think, especially when you're dealing with things like aquariums or concrete pours.

The process is straightforward. You measure the three dimensions of the space or object (length, width, and height), then multiply them together. The result is volume in cubic feet, as long as all your measurements are already in feet.

That last part trips people up. If you measure in inches, you need to convert before you multiply. Divide each inch measurement by 12 to get feet, then run the calculation. Same idea for yards (multiply by 3) or centimeters (divide by 30.48).

A quick cheat sheet for unit conversion before calculating:

• Inches to feet: divide by 12
• Yards to feet: multiply by 3
• Centimeters to feet: divide by 30.48
• Meters to feet: multiply by 3.281

Once everything is in feet, the multiplication is the easy part.

The formula is: Cubic Feet = Length (ft) × Width (ft) × Height (ft)

That's it. Three numbers, two multiplications. If you have a box that's 4 feet long, 2 feet wide, and 3 feet tall, the volume is 4 × 2 × 3 = 24 cubic feet.

For irregular shapes, things get a little more involved. A cylinder, for instance, uses a different formula (π × radius² × height). But for the vast majority of everyday situations like boxes, rooms, trucks, and containers, the length-times-width-times-height approach covers you completely.

If your measurements come in mixed units, don't try to shortcut it. Convert everything to the same unit first, then apply the formula. Mixing inches and feet in the same calculation is a fast way to end up with a number that's way off.

Boxes are the most common use case for this calculation. Shipping companies, storage facilities, and retailers all work in cubic feet when they need to know how much a box can hold or how many boxes fit in a given space.

Measure the inside dimensions of the box if you're figuring out capacity, or the outside dimensions if you need to know how much space the box itself occupies. That distinction matters when you're stacking boxes in a truck or a storage room.

Here's how the math looks for a few common box sizes:

For containers like refrigerators or chest freezers, manufacturers list the cubic foot capacity on the spec sheet, but it's good to know how to verify it yourself, especially when comparing older appliances that might not have that info handy.

Rooms are just big boxes. Measure the length, width, and ceiling height, multiply them together, and you have the cubic footage of the room. This comes up when sizing HVAC systems, calculating how much paint or insulation you need, or figuring out if a storage unit is large enough.

Storage units are typically advertised by square footage (a 10×10 unit, for example), but the actual usable volume depends on ceiling height too. A 10×10 unit with an 8-foot ceiling gives you 800 cubic feet of space. That context helps when you're deciding between unit sizes.

Moving trucks are rated in cubic feet as well. Common sizes run roughly like this:

• Small truck (10 ft): around 400 cubic feet, good for a studio or one-bedroom apartment
• Medium truck (15–17 ft): roughly 800–1,000 cubic feet, fits a two to three-bedroom home
• Large truck (20–26 ft): up to 1,800 cubic feet, handles larger homes or long-distance moves

When you're estimating whether your stuff will fit, a rough rule of thumb is about 150–200 cubic feet per furnished room. It's not exact, but it gives you a reasonable starting point before you start pricing out trucks.

These three units all measure volume, just at different scales. Cubic feet is the go-to for most everyday American uses. Cubic yards show up in landscaping, concrete, and large material orders. Cubic meters are the international standard and appear more in scientific or global shipping contexts.

If you order mulch or concrete and the supplier quotes you in cubic yards, just divide the cubic feet you calculated by 27. So if you need 54 cubic feet of topsoil, that's 2 cubic yards to order.

Converting to cubic meters works the other direction. Divide your cubic feet by 35.31 to get cubic meters. That conversion is mostly useful when you're dealing with international freight or working from metric blueprints.

Seeing the numbers in context makes everything click. Here are a few practical scenarios where cubic feet calculations come up regularly.

• Garden bed soil: A raised bed that's 8 ft long, 4 ft wide, and 1 ft deep holds 32 cubic feet of soil, which is about 1.2 cubic yards.
• Refrigerator capacity: A standard full-size fridge is typically 18 to 26 cubic feet. A 20 cu ft model measures roughly 28 in × 30 in × 66 in on the inside.
• Aquarium volume: A 55-gallon tank is about 7.35 cubic feet (since 1 cubic foot ≈ 7.48 gallons).
• Concrete for a slab: A patio slab 12 ft × 10 ft × 0.33 ft (4 inches thick) requires about 39.6 cubic feet, or roughly 1.5 cubic yards of concrete.
• Air conditioner sizing: A room that's 15 ft × 12 ft × 8 ft has 1,440 cubic feet of air volume, which helps determine the right BTU rating for the AC unit.

These aren't edge cases. They're the kinds of projects that come up all the time, and having the calculation right before you order materials or rent equipment can save you a real headache.

Getting the volume right has real consequences. Order too little concrete and you're making a second trip to the hardware store. Rent a moving truck that's too small and you're making two trips across town, or across the country. Underestimate a storage unit and you're paying for a second one.

Beyond cost savings, accurate cubic feet measurements matter for safety and compliance too. Shipping carriers calculate dimensional weight using volume, so if you're sending packages for a business, understanding cubic footage directly affects your shipping costs. Overloading a truck or storage space because you didn't check the volume limits can also create real safety issues.

For home improvement projects like insulation, HVAC, or ventilation, volume calculations are how contractors size equipment correctly. A system that's sized for the wrong cubic footage will either work too hard or not hard enough, and both scenarios cost money over time.

The math is simple. The payoff for getting it right is real. Whether you're planning a move, ordering materials, or just trying to figure out if that couch fits in the elevator, cubic feet is the number you need.