Cubic Feet Calculator

Created by Hanna Pamuła, PhD candidate
Last updated: Aug 01, 2021

With this cubic feet calculator, you'll quickly find out the volume in ft³. It may help you estimate the volume of a cuboid container, as well as the amount of material required to finish your desired earthworks - for example calculating cubic feet of soil, sand or gravel. In the paragraphs below, you can read about how to calculate cubic feet from inches, or from your favorite length unit. Wait no longer: scroll down, read on, and never worry about cubic feet calculations again!

How to calculate cubic feet?

"Calculating cubic feet" is a simplified way of saying that we need to find volume of an object in cubic feet. One cubic foot is a volume that fills a 1 ft x 1 ft x 1 ft cubic container.

Cubic container. One cubic feet volume.

So, if you want to calculate the volume of a box-shaped object, the formula for volume looks as follows:

Volume = length * width * height

If all your dimensions are in feet, then the volume you obtain is in cubic feet.

Calculating volume is useful in many different situations in everyday life, for example:

  • if you want to estimate the volume of your fridge, dishwasher or oven
  • you're curious how much space your suitcase takes up, so you'll know if it fits in your trunk
  • you're wondering how much sand will fit into a rectangular sandbox, or how much gravel your driveway needs, or
  • how much water will fill up your aquarium or pool (although gallons are used more often than cubic feet in those cases)

And how to calculate cubic feet from inches?

But what do we do if the dimensions are expressed in units other than feet - like yards, inches or even centimeters and meters? Well, you need to convert them. There are two ways of doing this - either you convert the units before the volume calculation or after:

  1. Convert the dimensions into feet

Assuming that our length, width, and height are in:

  • inches, you need to divide each value by 12
  • yards, multiply each value by 3
  • centimeters, divide each value by 30.48
  • meters, multiply each value by ~3.281

After converting the units you'll have all of the dimensions in feet, so a simple multiplication will give us the result in cubic feet.

  1. Convert the volume directly to cubic feet unit

You may find this method easier, as you only need to divide or multiply once:

  • divide the volume value by 1728 (12³) if the dimensions are in inches
  • multiply the volume value by 27 (3³) for dimensions in yards
  • divide the volume value by ~28316.847 (30.48³) for dimensions in centimeters
  • multiply the volume value by ~35.315 (~3.281³) for dimensions in meters

If you are dealing with a different unit for each dimension we recommend using first method to avoid miscalculations. Or, even better, you can use our cubic feet calculator and forget about tricky unit conversions!

Example on calculation of cubic feet from inches

Let's have a look at the example. Assume that you have an oven with its dimensions expressed in inches:

  • width = 30 in
  • height = 36 in
  • depth = 25 in

So, how do we calculate its volume in cubic feet? Let's find it using to two methods we outlined in the paragraph above:

  1. First, to calculate cubic feet from inches, we need to convert the inches into feet:
  • width = 30/12 ft = 2.5 ft
  • height = 36/12 ft = 3 ft
  • depth = 25/12 ft ~ 2.083 ft.

To find the final volume in cubic feet, we only need to multiply the dimensions together:

Volume = 2.5 ft * 3 ft * 2.083 ft = 15.625 ft³

  1. Alternatively, multiply all three dimensions together and divide the result by 1728:

Volume = 30 in * 36 in * 25 in = 27000 in³

Volume = 27000 / 1728 = 15.625 ft³

The result is, of course, the same. It wasn't so hard to calculate cubic feet from inches, wasn't it? Fear makes things look twice as bad as they are.

Calculating cubic feet of soil

Calculating cubic feet of soil is no different than calculating the standard volume! All you need to do is find the volume of soil required:

  1. Determine the area you want to cover with soil. If the area is rectangular, then it's a piece of cake - just multiply the length and width.

Area = length * width

Let's assume we have a length of 10 yards and a width of 3 yards, so then the area would be equal to:

Area = 10 yd * 3 yd = 30 yd²

If the area you want to cover has a more irregular shape, you can try dividing the area into a couple of rectangles and calculating their areas separately before sum them up. There are also situations where we want to cover a triangular, trapezoidal, circular or circle sector area. If you need a specific shape, e.g. cubic feet of a cylinder calculator (or a cone, or a sphere), check out our volume calculator which covers the most common three-dimensional solids.

  1. Decide on the desired thickness of the soil (also known as depth or height). Assuming that we want the same depth over the whole area, for example 0.5 yds, we need to calculate a volume of a rectangular cuboid (box):

Volume = Area * height = length * width * height

Volume = 30 yd² * 0.5 yd = 15 yd³

  1. Convert the result into the units you want - in this case, cubic feet. To convert from cubic yards to cubic feet, you need to multiply the result by 27:

Volume = 15 * 27 = 405 ft³

You can change the unit in the cubic feet calculator by clicking on the unit's name and choosing one from the drop-down list. Alternatively, you can use our volume converter.

And there we go, we've found the required volume of soil in cubic feet - 405ft³!

If this cubic feet calculator is too simple for your gardening needs, try our dedicated soil tool. Apart from calculating cubic feet of soil needed, it can estimate the cost and weight of the soil as well. We've prepared even more tools for gardening enthusiasts: check out our plant spacing calculator for how to plant the perfect line of plants, or the potting soil tool to estimate of amount of soil needed for containers of specific shapes.

Hanna Pamuła, PhD candidate
Cuboid container (rectangular prism). Cubic feet volume.
Volume in cubic feet
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