Landscape Rock Calculator
Quickly estimate cubic yards, tons, and material cost for your River Rock project. Adjust the inputs below and the result updates in real time.
Calculate Your Project
Estimate only. Add 10-15% for compaction and waste.
How this calculator works
River rock and decomposed granite are priced and delivered by the ton, so this calculator converts your measurements into a weight instead of stopping at volume. First it finds cubic yards: length in feet times width in feet times depth in inches, divided by 324. Then it applies the material's density, about 100 pounds per cubic foot, which works out to roughly 2,700 pounds per cubic yard, to convert that volume into pounds. Dividing by 2,000 turns pounds into tons, the unit you actually order and pay for. Because stone is far denser than lighter bulk materials, even a modest volume total can translate into a meaningful tonnage figure, which is why an accurate depth input matters for landscape rock.
What This Landscape Rock Calculator Computes
A landscape rock calculator turns three simple inputs, length, width and depth, into two numbers you can actually order: cubic yards and tons. River rock and decomposed granite sell by the ton, not the yard, so the calculator also converts your volume figure into a delivered weight using the material's density. Enter the length and width of the area in feet and the depth in inches, and the tool multiplies length by width by depth and divides by 324 to get cubic yards, then multiplies that figure by the material's pounds per cubic yard and divides by 2,000 to give you tons.
Depth Guidance for River Rock and Decomposed Granite
Depth changes the math more than any other input, so it pays to get it right before you calculate. A thin top dressing layer placed over an existing bed typically runs 2 to 3 inches. A standalone decorative area with no mulch or soil showing through usually calls for closer to 3 inches. Areas that need to resist erosion or handle light foot traffic, such as a dry creek bed or a border strip, often go 4 inches deep so the base stays stable. Decomposed granite compacts as it settles, so many homeowners plan for a slightly fuller starting layer than they would with loose river rock. Whatever depth you choose, keep it consistent across the whole area before you run the numbers, since a single average depth is what the calculator uses.
Density and the Yards to Tons Conversion
River rock weighs about 100 pounds per cubic foot, which works out to roughly 2,700 pounds per cubic yard. That density is what lets the calculator move from a volume figure to a weight figure, since a cubic yard of stone and a cubic yard of a lighter material are not remotely the same order weight. Multiply your cubic yards by 2,700 and divide by 2,000 to get tons. If you already have a cubic yard total from another project and just need the ton figure, run it through the cubic yards to tons converter, once instead of redoing the math by hand.
Ordering Tips and Overage
Order slightly more than the exact number the calculator returns. Uneven ground, low spots and settling after the first rain all eat into a bed that was measured to the pound. Adding roughly 10 percent on top of the calculated tonnage is a reasonable cushion for most residential jobs, and it costs less to have a small amount left over than to place a second delivery for a half ton shortfall. Measure the area in sections if it is not a simple rectangle, run each section through the calculator separately, and add the totals together before you order. If you are deciding between materials, compare River Rock and Decomposed Granite side by side, since they carry different look, drainage and compaction properties even though this calculator handles the tonnage math the same way for both.
Materials this calculator covers
From $54.20/ton- Size1 - 3″
- Density2700 lb/yd³
- ColorMixed natural
From $71.79/ton- Size0 - 1/4″
- Density3000 lb/yd³
- ColorTan, gold
From $43.24/ton- Size1/4 - 3/8″
- Density2800 lb/yd³
- ColorTan / mixed
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How much landscape rock do I need for my project?
Multiply the length and width of the area in feet to get square feet, then run that figure through this landscape rock calculator with your planned depth in inches. The tool converts the volume to cubic yards and then to tons using the material's density, so you get a delivered weight figure instead of a rough guess. Measure irregular areas in sections and add the totals for an accurate order.
What is the difference between river rock and decomposed granite?
River rock is smooth, rounded stone used mainly as a loose decorative or drainage material, while decomposed granite is a granular material that compacts into a firmer surface. Both are sold by the ton and both work with this calculator, but they behave differently once placed, so pick the one that matches whether you want loose stone or a walkable, compacted surface.
How many tons is one cubic yard of landscape rock?
One cubic yard of river rock weighs about 2,700 pounds, which works out to 1.35 tons. Other stone products can carry a different density, so the exact ton figure per yard depends on the material you select. Enter your area and depth into the calculator and it applies the density for the material you pick automatically, instead of you converting by hand.
Can I use square feet instead of cubic yards to order landscape rock?
Square feet alone will not give you an order quantity, since rock is sold by weight, not by surface area. You need a depth figure to turn a flat measurement into a volume, and a volume into tons. Measure your square footage, decide on a depth in inches, and enter both into the calculator so it can run the length by width by depth math for you.
Do I need to order extra landscape rock for waste?
Yes. Uneven ground, drainage dips and normal settling after installation typically use up more material than a flat, exact measurement suggests. Adding about 10 percent to the calculated tonnage covers most residential beds and paths without leaving a large surplus. If your site has significant grade changes, measure the deepest and shallowest points separately and average them before calculating.
What depth should I use for a landscape rock top dressing?
A top dressing layer placed over existing mulch or soil typically runs 2 to 3 inches deep. That covers the surface below without wasting material, though it is shallower than the 3 to 4 inches used for standalone decorative beds or areas that need better erosion resistance. Use one consistent depth figure across the whole area when you run the calculation.