How Much Crushed Stone Do I Need?

Calculate the Amount Required for Your Patio, Etc. Using This Formula

Image of a crushed-stone driveway.
Crushed stone, in addition to functioning as a base in DIY projects, can also serve as a driveway material. David Beaulieu

So you are planning this great DIY project for the summer that will spruce up your yard considerably. You are quite excited, but there is just one problem: It requires crushed stone, and you have no clue how to calculate how much you will need. Crushed stone is a material that is typically used as a base or underlayment, upon which the stuff that actually shows -- for example, the concrete of a patio -- will rest.

Guessing is rarely a good solution to such dilemmas when undertaking a big project, so let's look at a (relatively) simple way to figure out the correct amount.

The word, "relatively" is used because a formula is involved. And many of us, as soon as we hear the word, "formula," start quivering with fear. "What, math? Hey, I didn't sign up for this. I just want to do a DIY project. What sadist decided to make math part of it?" This is understandable, so some reassurance is called for. When the formula is actually provided for you (as opposed to your having to think up the formula, yourself), it is really pretty easy to use. All you have to do is plug in some numbers. So take a deep breath and let's get started:

Yes, It Is a Formula, but There Is No Need to Fear It

Use this formula to determine how much crushed stone you will need for your project:

(L'xW'xH') / 27 = cubic yards of crushed stone needed

In the construction world, most materials are measured in cubic yards. Multiply the length (L), in feet, by the width (W), in feet, by the height (H), in feet, and divide by 27. This will tell you how many cubic yards of crushed stone you need.

As an example, let's say your DIY project is a patio, and it calls for the use of crushed stone as a base.

If your patio is 20 feet long and 10 feet wide, and you need 6 inches of crushed stone for the base, you would plug those numbers into formula, like this:

(20'x10'x0.5') / 27 = 3.7 cubic yards

When using this equation, make sure all of your measurements are in feet. Since we needed 6 inches of crushed stone, we used 0.5 feet for the height (that is, we converted inches into feet).

If your number comes out as a fraction -- and it probably will -- round up. In the example above, you would round the 3.7 cubic yards of crushed stone to 4 cubic yards of crushed stone. It is better to have a little extra than to run short.

What Exactly Is "Crushed Stone?"

Crushed stone is produced by passing stones through a crushing machine at a quarry. Various types of stone are used in this operation, such as granite and limestone. At the bottom of the crushing machine lies a screen that traps the the crushed stone product (the finer material that passes through the screen is also kept and sold -- as stone dust).

What Other Uses Are There for Crushed Stone?

Above, mention was made of using crush stone as a base for various DIY projects, such as those that would involve pouring a concrete slab. But this material has a wide range of applications in the landscape.

While it often serves as a base for something else (in which cases no one actually sees it once the project is complete), this is not always the case. 

Other examples of how crushed stone can be used are:

  1. In roadways.
  2. As a driveway material.
  3. As a mulch in an area used as a dog run, in lieu of having your favorite mutt make a mess of your lawn.
  4. In a dry creek bed.