This river rock calculator will help you find how much river rock you need for your rock bed, no matter its area and depth. You can also use our tool as a river rock coverage calculator to know the area a specific volume or weight of river rock can cover. We have also equipped this tool with a river rock cost calculator, so you can also quickly know how much your river rock will cost you for your entire project.

In the article, you will learn how to calculate river rock volume and its corresponding weight using the densities of different river rocks. We will also briefly discuss the different types of river rock you can use for your projects. Keep on reading to learn more.

What are river rocks?

River rocks is the name for gravel and rocks found in the streambeds of natural water channels, like rivers or creeks. These rocks are usually round in shape and have smooth textures due to the friction from the water's continuous flow. They also come in a variety of colors depending on the minerals present in them. In specific locations, we may find many of the same rock types that we can collect and use at home. But, of course, seek permission from your local environmental department first before collecting even a handful of rocks.

Uniformly colored rocks can function as a decorative addition to an aquarium or can even be landscaped together with your mulch and neatly mowed lawn. We can also find river rocks used as a riprap or soil covering to avoid erosion and water runoff, or as backfill for french drains.

Other than that, we also use river rocks and other decorative rocks to give our home and garden a natural look as they can be used instead of pavers or concrete. However, the environment needs these stones too, so we have to know how much river rock we need to purchase to help conserve what we have.

How much river rock do you need?

The amount of river rock you need depends on the area you wish to cover with river rock and your desired river rock covering depth. The area and depth of your river rock bed is entirely up to you. So, if you really are planning to add river rock to your landscape, go ahead and measure up the area you wish to cover and we'll help you evaluate how much river rock you need.

Different types of river rocks

Before we proceed to the calculation of the volume and weight of your river rock, let us first explore some of the different river rocks we can choose from. River rocks vary in size, texture, and even color, and which one you use will depends on your taste. Some of these rocks may already be familiar to you, while some may be new:

Rock type
Density
(kg/m3)
Standard river rock
1425
Bank gravel
1483
Cheshire pink gravel
1545
Congo River rock
1314
Cotswold buff
1670
Cotswold Gold gravel
2098
Crushed asphalt
721
Crushed granite
1320
Crushed stone
1602
Crystal River rock
1522
Dolomite gravel
1865
Granite
2650
Ivory Coast gravel
1506
Pea gravel
1788
Peace River rock
1490
Quartzite
2700
Regular gravel
1346
Sunset gold gravel
1505
White marble chips
1430

In our table above, we have also included the densities of these rocks as we will be using these values to determine the weight of your river rock. Once you've decided which rock to choose, we can already start calculating.

How to use our river rock calculator

We equipped our river rock calculator with a variety of features that you might find helpful. To find how much river rock you need, here are the steps to follow:

  1. Select the type of river rock you wish to use. Upon choosing one, our river rock calculator will instantly display the density of that type of rock. Different river rocks have different density values, and so their total weight may be different.
  2. You can also directly input the density of your river rock if you wish.
  3. Enter the dimensions or the surface area you want to cover with river rock and its depth. This will instantly display the estimated volume of your river rock.
  4. Decide how much river rock you might waste when applying them to the area. You can also consider this as the contingency if the dimensions you entered in the fields are subject to change.

Using our tool as a river rock coverage calculator

You are at the right place to find how much area or square footage a certain volume or weight of river rock can cover. You first have to enter the volume or weight of the available river rock you have, whichever value is known for this requirement. Then input your desired river rock depth.

You will then instantly see the area coverage of your river rock. Play around with the calculator to explore which variables you can work out by filling in your known fields and leaving a particular variable empty.

At the very bottom, you will see the river rock cost calculator feature wherein you can enter the cost of river rock per unit volume or per unit mass to find the total cost of your selected river rock.

How do you calculate river rock volume and weight?

Now that we know how to use our calculator, either as a river rock coverage calculator or as a river rock cost calculator, wouldn't it be nice to also know how to calculate river rock's volume or weight on your own? All you have to do is find the volume that you want to fill with river rock by multiplying its dimensions together while considering the percentage of waste you might have, as shown in the equation below:

volume needed = (area * depth) * (1 + wastage)

After calculating the needed volume of river rock, multiplying its value by the density of this river rock will give you the corresponding weight of your river rock, like in this equation:

weight of river rock = volume needed * density of river rock

You can check your preferred river rock's density value in the different types of river rock section of this text.

Sample calculation of the amount of needed river rock

Let's say we want to make a 7.5-cm thick pea gravel (density = 1,788 kg/m3) walkway with a width of 80 centimeters (0.8 m) and a length of 10 meters. Using the formula we have and considering a 5% contingency or wastage, we estimate our needed river rock volume as follows:

volume needed = (area * depth) * (1 + wastage)

volume needed = ((0.8 m * 10 m) * 0.075 m) * (1 + 5%)

volume needed = (0.6 m3 * (1 + 0.05)

volume needed = 0.63 m3

If you need the volume in cubic feet or cubic yards, you can use our volume converter for the conversion. Nevertheless, when using our river rock calculator, you can easily change its units by just clicking or tapping on its units and selecting the unit you want.

Going back to the computations, to know how heavy this volume of pea gravel is, we evaluate its weight using the equation below:

weight of river rock = volume needed * density of river rock

weight of river rock = 0.63 m3 * 1,788 kg/m3

weight of river rock = 1,126.44 kg

We now know we need more than 1,126 kg of pea gravel for our walkway project from our calculation above. 🙂

FAQ

How much river rock do I need?

  1. Determine the area you wish to cover with river rock.
  2. Measure the desired depth of your river rock.
  3. Multiply the area by the depth to obtain the volume you need.
  4. Find out the density of the river rock you want to use.
  5. Multiply the volume by the rock's density to get its weight.

What are the applications of river rocks?

Due to their smooth texture and round shapes, we typically see them used as pavement for barefoot pathways in gardens, around swimming pools, and even in shower room floorings. When combined with other underground structures like perforated drainage pipes and other subgrade rock layers, they can also prevent water puddling and soil erosion.

How do I get river rocks for use at home?

You can check your local gardening supplies or hardware store for river rocks in your area. For small quantities, you can buy them in bags of various sizes. These suppliers may offer you a truckload of river rocks for larger projects, depending on their availability.

How do I landscape with river rocks?

You can use river rocks to pave your pathways or to surround your plants to protect the soil from erosion or from pets that like digging soil. Use light-colored river rocks for a cooler garden as they tend to reflect more sunlight than the dark-colored ones that absorb heat more.

How much does a yard of river rock cost?

Filling a square lot that measures 1 yard on both sides with river rock costs around $4-$7 per inch thickness. In other words, a cubic yard of river rock can cost around $150 to $250 depending on its color, rock diameter, and variation in sizes and shades. Typically, rounder rocks tend to cost more than irregularly-shaped rocks.

Kenneth Alambra
River rock specifications
Rock type
Standard river rock
Density
lb/cu ft
How much river rock do you need?
Length
ft
Width
ft
Area
ft²
Depth
in
Volume
cu yd
Wastage
%
Volume needed
cu yd
Weight needed
US ton
How much will the river rock cost you?
Price per one unit of mass
$/
US ton
Price per one unit of volume
$/
cu yd
Total cost
$
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