Stone dust is an extremely useful material for a variety of hardscaping projects. When installed properly, stone dust forms a solid, durable base that can support pavers or stones. However, calculating the right amount of stone dust you need for your project can be tricky if you don’t know what factors to take into account. In this comprehensive guide, we’ll walk you through how to calculate precisely how much stone dust you need for any project.

How Is Stone Dust Used in Hardscaping Projects?

Before we jump into the calculations, it’s helpful to understand the different ways stone dust is used in hardscaping projects.

Stone dust is most often used as a base material beneath patios, walkways, and driveways made of concrete, pavers, or stones. The stone dust forms a solid, supportive base that prevents shifting and movement of the finished surface.

A base of stone dust 4-6 inches thick is typical for most projects. The material is compacted down to form a sturdy sub-base, then the paving stones or materials are laid on top. The stone dust fills in any gaps, creating a consistently level surface.

Stone dust is also used as filler between paving stones. Once the pavers are laid into place, stone dust is swept into the joints to help hold the pavers together and prevent weeds and grass from growing in the joints. Typically 1-2 inches of stone dust is used for these joints.

Knowing the main ways that stone dust is utilized will help you calculate how much you need based on the details of your specific project.

What Type of Stone Dust Should You Use?

Stone dust comes in a few different varieties, each with their own unique properties and uses. It’s important to get the right stone dust for your specific needs.

Stone Dust Types:

Concrete Sand: A general purpose mix used beneath pavers and other masonry work. It packs tightly and forms a sturdy base.
Paver Base: Specifically made for use beneath pavers and patio stones. Contains a blend of stone dust and other materials that forms an exceptionally solid base.
Decomposed Granite: A fine powder made from crushed granite used for pathways and fill between flagstones. It compacts tightly but allows for some drainage.
Stone Dust Fines: The finest particles and powder from stone crushing. Used for paver joints and as paver edge restraints. Packs down smoothly.
Washed Stone Dust: Stone dust that has been rinsed of all fine materials. Used where drainage is important. Not ideal for paver bases.
Polymeric Sand: Sand blended with polymers to form durable joints between pavers. Resists ants and weeds when wet.

Get the variety suited for your particular project needs. Most commonly concrete sand or paver base works well under patios and walkways, while stone dust fines create solid paver joints.

Calculate Needed Base Depth

The first calculation you’ll want to make is how deep your stone dust base needs to be.

This depends on a few factors:

Type of Ground Surface: Compact soil or gravel needs 4″ depth. Sandy or poor draining soil needs 6″+.
Project Type: Patios and sidewalks need 4-6″. Driveways need a minimum 6″ depth.
Climate Conditions: Cold climates should have 6″ for freeze protection. Hot climates can get by with 4″.
Type of Traffic: Heavier traffic from vehicles requires 6″+, while light foot traffic needs 4-5″.

For most patio and walkway projects, a depth of 4-6 inches of stone dust is appropriate. Driveways may need 6 or more inches. Gauge your specific project needs and soil type to decide.

If building on poor soil, it’s better to err on the side of too much depth rather than too little.

Calculate Coverage Area

To know how much stone dust to purchase, you first need to calculate the square footage of the area you’ll be covering.

Carefully measure the length and width of the space in feet, then multiply to find the total coverage area.

For example:

Patio Length: 20 feet
Patio Width: 15 feet
20 ft x 15 ft = 300 square feet

Be sure to calculate separate areas like a walkway and patio separately, then add all the coverage areas together.

When calculating irregular shapes, break the area down into smaller rectangles and triangles to get a more accurate measurement.

Having the precise base coverage area is crucial for determining how much stone dust you need. Don’t guess the measurements or you may find you don’t have enough material later on.

Calculate Cubic Yards Needed

With the base depth and square footage calculated, you can now determine how many cubic yards of stone dust you’ll need.

Cubic yards are simply the area multiplied by depth in feet.

So for example:

300 sq ft coverage area
4 inch (0.33 ft) depth
300 x 0.33 = 99 cubic ft of stone dust needed

Since cubic yards are the units used by most suppliers, you need to convert the cubic feet to cubic yards by dividing by 27.

So for our example:

99 cu ft needed
99 / 27 = 3.66 cubic yards needed

Round up and you would need 4 cubic yards of stone dust for a 300 sq ft area with a 4 inch depth.

Follow these same steps using your measurements to calculate how many cubic yards you need. Having the exact yardage will ensure you buy the right quantity so none goes to waste.

Estimate by Bag Instead of Yards

Stone dust is also often sold by the bag instead of by the cubic yard. Bags are easier to transport in smaller vehicles.

To estimate how many bags you need instead:

Calculate cubic feet needed (area x depth in feet)
Assume 0.8 cubic feet per bag (based on typical 0.5 cu ft bags)
Divide cubic feet needed by 0.8 cu ft per bag

So for example, with 300 sq ft area and 4 inch depth:

300 sq ft x 0.33 ft depth = 99 cu ft
99 cu ft / 0.8 cu ft per bag = 124 bags

You would need about 124 bags of stone dust for a 300 sq ft area at 4 inch depth.

Bags allow flexibility if you just need a small amount, though cubic yards are cheaper for large projects.

Estimate for Paver Joints

When installing pavers or stone, you’ll also need extra stone dust to fill in the joints after laying the pavers.

The typical guideline is you’ll need about 10% extra stone dust for the joints.

So if you needed 1000 lbs of stone dust for the base, you’ll want another 100 lbs (10% extra) for the paver joints.

Having that extra joint material available ensures you don’t run out right at the end when finishing your project.

Buying Stone Dust Tips

Now that you know precisely how much stone dust you need, here are some useful tips for purchasing:

Buy 10-15% extra. It’s better to have leftover than run short.
Have it delivered rather than transporting yourself. Fees are often affordable.
Purchase from landscape supply stores for better quality and service than big box stores.
For large projects, compare cost of cubic yards vs bags. Yards are often more economical.
Let stone dust dry out before compacting if it was purchased damp.

Accurately calculating how much stone dust you need may take a little time upfront, but it will save you the headache later of having to make extra trips to purchase more. Carefully measure, calculate, and purchase the right amount with a little extra to ensure you have plenty available to complete your hardscaping project.

Frequently Asked Questions About Calculating Stone Dust Needs

How much stone dust do I need under pavers?

For a paver base beneath a patio or walkway, you typically need a 4-6 inch depth of stone dust. Calculate the square footage of the area, then multiply by the depth in feet to get cubic yards.

Does stone dust compact over time?

Yes, stone dust will settle and compact over the first few months after installation. It’s best to overcalculate your needs slightly to account for this natural settling.

Can stone dust be used for drainage?

Some types of stone dust like washed stone screenings can assist with drainage under surfaces. But for solid bases, you want finer non-draining stone dust.

What is the difference between stone dust and sand?

Stone dust is made from crushed stones and is more solid and coarse than sand. Sand tends to shift more easily under foot traffic, while stone dust locks tightly together.

Is a bag of stone dust 0.5 cubic feet?

Bag sizes vary, but a common size is 0.5 cubic foot bags. Check your supplier as some bags may be 0.4 cu ft or other sizes. Measure bags to confirm volume if the size isn’t marked.

Do you compact stone dust in layers?

For bases over 6 inches thick, it’s best to compact stone dust in layers no more than 4 inches thick. Compact each layer fully before adding the next layer.

When should you use polymeric sand vs stone dust?

Use polymeric sand specifically for filling the joints between pavers and flagstones. The polymers lock the material together. Use stone dust under the surface and for edge restraints.

Can I use stone dust for patio elevation?

Yes, you can build up low areas by spreading stone dust. Compact in layers no more than 4 inches per layer to prevent settling.

Is stone dust better than gravel?

Stone dust forms a more solid base for pavers that won’t shift out of place. Gravel bases have a tendency to spread apart, causing paver movements.

How do I calculate coverage area for a round patio?

For a round or curved patio, estimate the length and width or diameter to get approximate rectangle area. Or, use an online pattern calculator tool to determine square footage.

Conclusion

Calculating the ideal amount of stone dust for your hardscaping project doesn’t need to be difficult, as long as you carefully measure your coverage area and base depth needs. Figure the square footage, depth in feet, and do the cubic yard calculations. Buy 10-15% extra to have plenty of material available with some left over.

With the right quantity of stone dust purchased for your needs, you can create a solid base and finish the joints between pavers to produce a durable surface that will stand the test of time. Precise calculations result in a smooth installation process and a finished patio, walkway or driveway that you can enjoy for many years.

Calculating How Much Stone Dust You Need