Crushed Stone Calculator

While planning your DIY project or re-graveling a patio area or driveway, you’ll want an accurate estimate to use to figure out how much material you’ll need to complete the job. Whether you’re a contractor or a homeowner, and whether you’re looking for pea gravel or ¾ inch crushed, there’s an easy way to figure out how much you need.

Most companies sell their crushed stone by either the cubic yard or the ton. It’s best to figure your needs by the cubic yard and then use one more step to convert to tons.

On This Page:

1. How to Calculate Crushed Stone
2. Real-World Calculation Example
   1. Circular Areas
   2. Calculating Crushed Stone by Weight

How to Calculate Crushed Stone

To get to the total volume of crushed stone that you will need, measure the width, length and depth of your project. A good rule of thumb for the depth of crushed stone projects is to calculate a minimum of 2-4 inches. Some projects need more than this, but this is a good starting point. Note that you’ll need to convert your depth into feet by dividing it by 12.

The complete formula to figure out how many cubic yards of crushed stone you’ll need is:

(Length x width x depth)/27

This final number is how many cubic yards of material you will need.

Real-World Calculation Example

First, calculate the area in square feet of your project. As an example, a 10-foot wide, 20-foot long driveway is a 200-square foot area. Then, multiply the area by the depth. For instance, if you are using four inches of crushed stone under a patio area or for a driveway, four inches converted to feet is .33. So, our calculation is .33 x 200 ÷ 27, or 2.46 cubic yards.

Circular Areas

Circular areas require a little more math to yield exact measurements. If you’re happy with an approximation, you can measure the diameter in two directions, multiply those as you would a rectangular area, and subtract 20 percent. If you want to be exact:

1. Divide the diameter of the patio in half to find the radius.
2. Multiply that by itself (square it).
3. Multiply the result by 3.14, also known as pi.

For example, say your patio is 16 feet from edge to edge. The radius of your patio is half of 16 feet, or 8 feet. Eight feet squared is 64 feet. Sixty-four feet multiplied by 3.14 equals about 201 square feet.

Using the 20 percent method, we would multiply 16 by 16 to reach 256. Then calculate 80 percent of that by multiplying 256 by .8. That total is 204.8, rounded to 205. A four-square-foot difference of crushed gravel isn’t going to affect your price or your project significantly, so you can feel comfortable choosing whichever method you like.

Calculating Crushed Stone by Weight

A final calculation is if you need to figure out the weight in tons of your crushed stone. You might not need to figure this out, but it’s handy to know. Most gravel weighs about 1.5 tons per cubic yard. So, for the examples above, 2.45 cubic yards of gravel weighs 3.68 tons or 7,350 pounds.

This formula may seem like a lot of math, but an accurate material calculation will help you stay within budget and is a substantial factor in the success of your project.

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