River Rock Calculator for Beds, Borders and Dry Creek Lines
Enter your project dimensions
Pick up one stone from the bed you are planning and measure across it. That single reading decides more than the size of the bed does, because river rock has to lie about twice as deep as the stone is wide before the ground underneath stops showing through. An inch of stone wants two inches of layer. Three-inch stone wants four or more. The river rock calculator above converts a bed into tons, and the depth you hand it is the number worth arguing over.
Depths for the beds a Carolina yard actually has
| The job | Stone size | Depth to enter | What one ton covers |
|---|---|---|---|
| Strip under the drip line at the foundation | 3/4 to 1 inch | 3 to 4 inches (deeper than the rule, for roof runoff) | about 80 sq ft at 3 inches |
| Splash pad below a downspout | 1 to 3 inch | 3 inches | about 80 sq ft |
| Dry creek line carrying storm runoff | 1 to 3 inch | 4 inches | about 60 sq ft at 4 inches |
| Mow strip along a fence line | 3/4 to 1 inch | 2 inches | about 120 sq ft |
| Ring around a tree or a post | 3/4 to 1 inch | 2 inches | about 120 sq ft |
| Anchor stones set into a creek line | 2 to 4 inch | 4 to 5 inches | about 53 sq ft |
The foundation strip is the one people set too shallow. Three to four inches over fabric, graded to fall away from the wall, both looks finished and keeps roof water moving; two inches there will show its fabric by the second summer.
Sending a creek line, a mow strip and four splash pads through at once
Switch between Rectangle, Circle and Multiple areas at the top of the form. Lengths, widths and a circle's diameter all go in as feet, and up to five areas can be added before you calculate, which is how a set of downspout pads and a border get totaled in one go. Depth is in inches and the box takes anything between 0.25 and 24.
Set the Material select to the rock you are buying so the weight matches, then decide about the tick marked "Add 5% extra for compaction & spillage". It is optional and it is the only allowance the form carries. On loose decorative rock that nothing will roll, five percent is about the spillage between the pile and the bed. Press Calculate material needed and the answer comes back in cubic yards, tons and cubic feet together. "Email my quote" keeps a copy, which saves re-measuring when the beds get ordered a week later.
A 28-foot creek line and the strip along the front of the house
Both are illustrative, not customer work.
The creek line runs 28 feet from the corner of the garage down to the property line, averaging 4 feet across, in 1 to 3 inch rock at 4 inches. 28 x 4 = 112 square feet. 112 x 4 / 12 = 37.33 cubic feet. 37.33 / 27 = 1.38 cubic yards. At 1.35 tons a yard that is 1.87 tons, or 1.45 yards and 1.96 tons with the five percent ticked.
The foundation strip is 50 feet by 2.5 feet in 3/4 to 1 inch rock at 2 inches, which is the shallow end of what that size will cover. 50 x 2.5 = 125 square feet. 125 x 2 / 12 = 20.83 cubic feet. 20.83 / 27 = 0.77 cubic yards, or 1.04 tons. Take it to 3 inches and the same strip needs 1.16 yards and 1.56 tons, which is the half ton that decides whether the fabric stays hidden.
Four splash pads at 3 by 2.5 feet each, in 3 inches of the same 1 to 3 inch stone, come to 30 square feet altogether. 30 x 3 / 12 = 7.5 cubic feet, which is 0.28 cubic yards and 0.38 tons. That is the sort of quantity worth folding into a larger order rather than chasing on its own.
Twenty-seven hundred pounds a yard, and the pile that looks short
River rock at 1 to 3 inches is figured at roughly 2,700 lb a cubic yard, which is 1.35 tons, and that is the site's own published weight. Read it the other way and a delivered ton is about three quarters of a cubic yard, which is why a tipped pile so often looks smaller than the number on the paperwork suggested. The yardage is the honest measure of how much ground you can cover; the tonnage is what the truck is carrying.
Size changes the coverage, not the weight. The same ton of 3/4 to 1 inch rock at 2 inches deep reaches about 120 square feet, while at 3 inches it reaches about 80, and 2 to 4 inch rock laid at its proper 4 to 5 inches gets to roughly 53. Doubling the stone size roughly halves what a ton will cover, so a change of mind at the yard about stone size is a change to the order, not just to the look.
Fabric first, except where water is actually moving
Bare Piedmont clay swallows stone. The rock settles a little each wet season, weeds find the gaps, and three years later the bed needs topping up. Pin non-woven fabric down before any decorative rock goes on. The exception is stone in an active drainage run, where the fabric wraps around the stone instead of lying beneath it, so silt is kept out of the voids rather than washed into them.
While the rock is going down, use two sizes rather than one. A bed of a single uniform size reads as a median strip. Start with the 1 to 2 inch material, then set groups of larger stones into it, and bury the biggest creek-line anchors about a third of their height so they look water-worn rather than delivered. Hose the bed off once it is spread, because delivery dust dulls the color until it is rinsed.
Buying for the front edge, which is where it goes thin first
Round the tonnage up rather than down. The edges of a bed are where rock migrates, where a mower catches it and where a thin patch is noticed from the sidewalk, so a spare few hundredweight has somewhere obvious to go: a double layer along the front foot of the bed. Leaves come off with a blower on a low setting rather than a rake, which throws stones into the grass.
Rock is not always the right answer for a planted bed either. Stone holds heat against the soil through a Carolina summer, so borders, drainage lines and edges take rock well while beds full of shrubs are usually happier under bark; put the same dimensions through the mulch calculator and compare the two quantities before you commit. A seating area or a path that wants something softer underfoot is a job for the pea gravel calculator instead.
When the number is settled, open the page for the size you want and choose a quantity and a date there. River Rock covers the common bed and border sizes, Large River Rock suits creek beds and heavier erosion work, and Drain Rock is the one for a run that has water moving through it. Delivery is set at checkout by ZIP code, and the truck needs a clear spot to tip where the pile will not be in the way of the wheelbarrow. If the bed is going over a slope or a wet line, the locations page for North Carolina and the contact page are both quicker than guessing.
Common questions
The bed runs down a bank. Do I measure the slope or the flat distance?
Measure along the face of the slope, tape laid on the ground, because that is the surface the rock has to cover. A bank that is 12 feet across on a plan can be 14 feet down the face, and on a long border that gap is a ton. Enter the slope length as your length.
The border turns the corner of the house in an L. Does that need two calculations?
One calculation with two areas. Choose Multiple areas, put the long leg in as one rectangle and the short leg as another, and stop the second leg where the first one ended so the corner is not counted twice. The result comes back as a single total.
There is a steel edging strip around the bed. Do I measure to it or inside it?
Inside it. Rock only fills the space between the edges, and the strip itself takes up an inch or two of real width on every side. On a narrow mow strip that can be a tenth of the area, which at 2 inches deep is worth knowing before you order.
The creek line needs drain stone underneath and river rock on top. How do I order that?
Run the calculator twice with the material select moved between the runs, since drain rock and river rock do not weigh the same by the yard. Enter the depth of each layer separately rather than the total depth, then order the two products from their own pages.
The bed is a curve with no straight side anywhere. What do I type?
Either box it into a rectangle that just contains the planted shape and use the small overage along the front edge, or cut it into two or three rectangles in Multiple areas. A rounded bed with an obvious middle can also go in as a circle measured across the widest point, which lands close enough for decorative stone.
Related calculators
Rock beds are a one-time buy.
River rock, large river rock and drain rock by the ton, free delivery included.
