Rock Calculator

Use this rock calculator to plan a landscaping project before you order the required materials. Buying too little can delay your project, while buying too much can unnecessarily increase the cost.

Our tool makes this process easier by using the rock type and density, together with the area’s shape and dimensions. It can then estimate the volume, total weight, and cost of the material you need. We also have a gravel calculator and a river rock calculator dedicated to special rock types. Be sure to check them out!

Using the rock calculator takes just a few steps:

1. Select the type of rock. The calculator will display its density. If your material isn't listed, select Other and enter its density manually.
2. Select the shape of the area to fill with rocks. You can choose a rectangle, circle, or triangle.
3. Enter the dimensions. Provide the required measurements and the depth of the area you want to fill. For a triangle, you can calculate its area using the base and height or enter all three sides.
4. Check the results. The rock calculator shows the volume to fill, the rock’s weight, and the final weight including waste.
5. Adjust the waste factor if necessary. The default is 10%, but you can change it using the corresponding option.
6. Calculate the total cost. Open the last section of the calculator and enter the unit price of the rock to see the estimated total cost.

Rock volume

The amount of rock you need depends mainly on the area you want to cover and the depth of the rock layer. In practice, you need to:

1. Calculate the area of the space you want to fill. The rock coverage calculator includes three basic shapes, but for more complicated shapes, you may need to find the area manually.

2. Multiply the area by the required depth to get the volume of the rock you need.

Rock weight

If your supplier offers rocks by weight, you need to express it in units of mass. Let’s see how to figure out rock tonnage:

1. Once you know the volume, check the rock’s density. You can usually find this information on the supplier’s website.

2. Multiply volume by the density to get the weight of the rock occupying that volume. By paying attention to the units, you can calculate the rock’s weight in tonnes.

It’s also a good idea to account for some material waste. This rock tonnage calculator uses a 10% waste factor by default, but you can adjust it to suit your project.

The cost of rocks for landscaping depends on several factors, including material type, quantity, and local prices. Rock is commonly sold by weight, for example, by the tonne or ton, although some suppliers may use other units.

To estimate the total cost, multiply the required amount of rock by its unit price:

Total cost = Final weight × Unit price

For example, if your project requires 4 tons of rock after accounting for waste and the material costs $50 per ton, the estimated total cost would be $200.

One ton of rock can cover a different area depending on the type of rock and the depth of the layer. Denser rocks provide less coverage by volume, while lighter materials cover a larger area. The deeper you spread the rock, the smaller the area 1 ton will cover.

Let’s use this base rock calculator to find the coverage of 4 inches of gravel:

1. Enter the gravel weight of 1 tonne into the rock coverage calculator’s results. Yes, you can do the inverse calculations! Be sure to use the correct units. Our tool says 1 US ton of gravel occupies about 17.8 cu ft of gravel.

2. Enter the depth. If you do the calculations by hand, be sure to express inches of depth in feet, i.e., 4 in ≈ 0.33 ft.

3. Our tool will give you the final answer immediately. It will simply divide volume by depth to get the area:

   17.8 cu ft / 0.33 ft ≈ 54 sq ft

4. So, with 1 US ton of gravel, you can fill 54 sq ft of space, assuming the depth is 4 in.