How Much Crushed Stone Do I Need?

Calculate What's Needed for Your Patio, Driveway, or Yard Using This Formula

closeup of crushed stone

The Spruce / K. Dave

When it comes to DIY projects it can be a challenge to figure out exactly what you need in the way of materials. This is the case when you want to spruce up your yard with walkways, install a patio, or improve your driveway, Crushed stone is a good material to use for lots of projects like these and is available in a variety of colors, textures and sizes. But the dilemma is to determine how much crushed stone you will actually need.

With this relatively simple formula, you can calculate how much you need by plugging in a few numbers.

Crushed Stone Project Formula

Formula for Crushed Stone for a Project

(L' x W' x H') / 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 number is 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 the following formula:

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

When using this equation, make sure all your measurements are in feet. Since you need 6 inches of crushed stone, you use 0.5 feet for the height (convert inches into feet).

If your number comes out as a fraction, 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 Is Crushed Stone?

Crushed stone is a man-made construction aggregate typically produced in a quarry by passing stones through a crushing machine. It is generally used as a base or underlayment, for example, where the concrete of a patio will rest. It's also used for drainage and landscaping. It is offered in a variety of sizes and stones. Sizes range from No. 1, which is the largest available type at 2 to 4 inches, to a 3/4 inch variety used in asphalt mixes and driveways. Crushed stone can be purchased at home improvement stores, garden centers, or directly from a quarry. There are many types of stone;

  • Argillite: This dark blue rock has flecks of green and red and is a durable, highly compact sedimentary or metamorphic rock made of clay or silt. It's stronger than shale and doesn't cleave like slate. It has fine grains and a rough, dull texture that can be polished to shine. It can resist heat, impacts, water, scratches, staining, wind, and acid, and is commonly used as a component in cement and mortar.
  • Basalt: Basalt is an igneous rock that formed from molten rock material (lava or magma). It is typically a dense dark rock colored blue, grey-blue, dark-grey, or black with a fine-grained texture. It is commonly crushed for use in construction projects, including roads, concrete, and asphalt.
  • Gabbro: Sometimes called "black granite," gabbro is a coarse-grained, dark-colored igneous rock. It is usually black or dark green, made of plagioclase and augite minerals. It is the most abundant rock in the deep oceanic crust and is commonly used as the crushed stone base at construction sites, countertops, floor tiles, and pavers.
  • Granite: Granite refers to any light-colored igneous rock that is used in construction. It is a household favorite, chosen for its color and durability. The igneous rocks in this group are called granite, granodiorite, diorite, and rhyolite.
  • Grit or gritstone: This is a hard, coarse-grained sandstone. It's basically a coarse sand that may contain small pebbles. It is commonly used as construction aggregate.
  • Limestone: Made of calcium carbonate, it is the most popular crushed stone option. Limestone is easily crushed and used in cement, ready-mix concrete, and is the foundation construction material for roads, buildings, and railroads.
  • Quartzite: Quartzite is sandstone that has gone through metamorphisis; it has heated and compressed, welding into a durable rock that can be difficult to mine, handle, and transport. It is also used for road construction, rubble, and in between railroad tracks.
  • Recycled stone substitutes: Crushed stone substitutes include sand and gravel, splintered or expanded clay or shale, perlite, vermiculite, and slag. Iron and steel slag are the byproduct rocks that result from smelting ores.
  • Riprap: Layer of larger stone, cobbles, or boulders; it can be a variety of rocky material, ranging from 4-inches to 2 feet in size. It is used for erosion control or slope stabilization.
  • Sandstone: Made by sand cemented together by calcite, clay, or silicate minerals. Water can seep into the spaces in this material making it porous. This option is not popular for long-term use in areas with freeze-thaw cycles which can break apart the stone.
  • Slate: This fine, clay metamorphic rock is commonly used for sidewalk slabs, roofs, flooring, countertops, and chalkboards. It can range in size from small pieces of rocky grain to 1.5 inches in diameter, and the color varies from black and gray to hues of red, blue, and purple.
  • Volcanic scoria: This volcanic rock was formed with voids where gas bubbles were trapped as the rock solidified. Freeze-thaw cycles and heavy weight can make these rocks break down over time. It's lightweight to transport and popular for landscaping, planters, gas grills, and roofing granules.
  • Washed gravel: Cleaned of all dirt and dust, this landscaping rock looks like smooth river rocks. The individual rocks are about 1 to 2 inches in diameter. Washed gravel has the appearance of river rock, which means it is often more affordable than actual river rock. You can use this gravel for pathways, driveways, play areas, grilling areas, and most all outdoor areas.

Did You Know?

In 2020, the Unites States produced 1.46 billion tons of crushed stone, according to the U.S. Geological Survey. That's an average of about 4 tons of crushed stone per American.

Crushed Stone vs. Gravel

Crushed stone is any stone that has passed through a machine and is made smaller in size. In contrast, gravel is produced naturally. It's made smaller and smoother due to the natural process of erosion and weathering over time. The cost of gravel and crushed stone will vary depending on where you live, the specific type, and how much of that product you will need. Pea gravel is smaller-sized gravel, roughly pea-sized.

Crushed stone is commonly used as an aggregate for construction, including roadways. It is also used in landscaping and gardens. The angular surface, roughness, and larger crushed stone make it a popular choice for gardens and pathways. It provides solid traction, doesn't easily sink into the ground, and resists weed growth. But, it's not easy on bare feet, so it is rarely used for backyard walkways or patio flooring near pools. You can use it for a gravel driveway as the middle layer. In gravel driveways, the middle layer is typically golf-ball-sized crushed stone.

By comparison, gravel has a rounder, more natural appearance and is a cost-effective option. Gravel is used mainly for driveways, although you can use it for paths, patios, dog runs, and playgrounds. One disadvantage of small, pea gravel is it will move easily if not appropriately edged. If you're going to add it to a walkway or a flower bed, be sure to add concrete blocks or landscape trim to keep it in place.

Comparison between crushed stone (left) and Pea gravel (right)
Crushed stone (left) and Pea gravel (right)

R.Tsubin and 1stclassphoto / Getty Images

What Other Uses Are There for Crushed Stone?

Limestone as an Acid Neutralizer

Limestone is an alkaline agent that can raises the soil pH. It also mixes well with fertilizer. After it rains, the lime runs into the dirt and helps to nourish your plants, prevent harmful lawn toxins from building up, and improve the soil's calcium levels.