River Rock Calculator
Calculate how much river rock you need in cubic yards and tons. Pick the stone size and the calculator sets the layer depth and shows the square feet one ton covers.
By CalcBuilt Editorial TeamUpdated September 9, 2026Formulas checked against manufacturer specs, see how we calculate.
Results
- River rock needed
- 3.33 cu yd
- 90 cu ft of 1 to 3 in washed stone
- Weight to order
- 4.5 tons
- 9,000 lb at 1.35 tons per cubic yard; quarries publish 1.35 to 1.5 for wet or dense stone
- Area covered
- 360 sq ft
- At 3 in deep, one ton covers about 80 sq ft
- Wheelbarrow loads
- 36 loads
- Stone loads a barrow by weight, about 2.5 cu ft or 250 lb per trip, so a bulk pile moves slowly
River Rock formula
Cubic feet = Length (ft) x Width (ft) x Depth (in) / 12
Cubic yards = Cubic feet / 27
Tons = Cubic yards x 1.35
Sq ft per ton = 20 cu ft per ton / (Depth (in) / 12)Worked example
A dry creek bed 40 ft long and 3 ft wide in 3 to 5 in rock, laid one stone deep at 4 in: 40 x 3 x (4 / 12) = 40 cubic feet, or 1.48 cubic yards. At 1.35 tons per yard that is 2 tons, and at 60 sq ft per ton the 120 sq ft checks out. At $130 per ton the stone is $260 plus delivery.
A 200 sq ft foundation bed in 3/4 to 1 in rock at 2 in deep needs 33.3 cubic feet, or 1.23 cubic yards and 1.67 tons. In bags that is 67 bags of 0.5 cu ft, which is why anything past half a yard goes bulk.
Quick reference
| Rock size | Layer depth | Cu yd per 100 sq ft | Tons per 100 sq ft | Sq ft per ton |
|---|---|---|---|---|
| 3/4 to 1 in | 2 in | 0.62 | 0.83 | 120 |
| 1 to 3 in | 3 in | 0.93 | 1.25 | 80 |
| 3 to 5 in | 4 in | 1.23 | 1.67 | 60 |
| 5 to 8 in | 6 in | 1.85 | 2.50 | 40 |
| 3 to 5 in, creek bed | 8 in | 2.47 | 3.33 | 30 |
Size the stone first, then the depth
Coverage follows the stone size, because a rock bed is laid one stone deep. Spreading 3 to 5 inch rock 2 inches deep leaves gaps you can see the fabric through, and spreading 3/4 inch rock 6 inches deep buys three times the stone for the same look. Use 3/4 to 1 inch for paths and small beds at 2 inches, 1 to 3 inch for general beds at 3 inches, 3 to 5 inch for dry creeks and downspout splash zones at 4 inches, and 5 to 8 inch where runoff has to be slowed.
Dry creek beds and armored slopes are the exception: they run 1.5 to 2 stones deep so water moving through the bed cannot lift a single layer. Mix sizes there. A creek reads as natural when a few boulders sit proud of the bed, medium rock fills the channel, and the smallest stone works into the gaps.
Fabric, edging and moving the pile
Fabric under rock buys a few clean seasons, not permanent weed control. Weeds germinate in the dust and leaf litter that collects on top, root through the weave, and the fabric then comes up in shreds. Use a woven geotextile for separation on paths and driveways where the job is keeping stone out of soil, and plan on spot spraying beds either way. Both extension guides that back this page make the same point about plastic and weed cloth in landscape beds.
Rock beds also change the soil around plants. Stone reflects heat back at foundation walls and at anything planted in it, so keep river rock for foundation shrubs, xeric plantings and drainage, and keep it out of vegetable and annual beds where you dig every year. Moving it is the part people underestimate: bulk stone comes in one pile, a wheelbarrow takes about 2.5 cubic feet of rock before it is too heavy to steer, and 5 tons is roughly 40 loads. Order all the stone in one delivery, since the fee is typically $75 to $150 per load whether you take 2 tons or 10.
What this calculator leaves out
Geotextile fabric, edging and stakes, excavation and haul-off of the soil the rock replaces, and the delivery fee. It also leaves out the base under a rock path, drainage pipe in a dry creek that carries real flow, plants and their planting holes, and the leaf blower or annual top-up that keeps a rock bed looking new.
Mistakes that cost money
- Rock spread on woven fabric still grows weeds, because silt and leaf litter build a seedbed on top within two seasons.
- One-inch stone in a dry creek moves in the first heavy storm; size the rock to the flow and set the largest along the outside of bends.
- Rock in an annual or vegetable bed cooks the soil surface and cannot be removed later without screening every yard of it.
- No edging beside a lawn: the mower throws stone, and stone in the bed line ruins a mower blade and a string trimmer head.
- A ton of stone is only 20 cubic feet, so a half-ton pickup takes about half a ton and a 5 ton order is 10 trips.
- Rock piled against siding or over a stucco weep screed traps water; keep the surface 4 in below the screed or the siding line.
Key facts
- Washed river rock weighs about 1.35 tons per cubic yard, so one ton is roughly 20 cubic feet of stone.
- One ton covers about 120 sq ft at 2 in, 80 sq ft at 3 in, 60 sq ft at 4 in and 40 sq ft at 6 in.
- A rock bed is one stone deep: 3/4 to 1 in stone needs 2 in, 1 to 3 in needs 3 in, 3 to 5 in needs 4 in, 5 to 8 in needs 6 in.
- Rock does not break down, so a bed is a permanent installation; extension guides class it with foundation plantings, not vegetable beds.
- Stones under about 1/2 in let rain soak in like a mulch, while larger stone sheds more of a hard rain as runoff.
Frequently asked questions
How much does a ton of river rock cover?
About 120 sq ft at 2 in deep, 80 sq ft at 3 in, 60 sq ft at 4 in and 40 sq ft at 6 in. One ton is roughly 20 cubic feet of washed stone.
What size river rock should I use?
3/4 to 1 in for paths and tight beds, 1 to 3 in for general landscape beds, 3 to 5 in for dry creeks and splash zones, and 5 to 8 in where water runs fast. Smaller stone shifts underfoot, larger stone is hard to blow clean.
How many cubic yards is a ton of river rock?
About 0.74 cubic yards, since river rock runs roughly 1.35 tons per cubic yard. Ask the quarry for its own number before ordering, because dense or wet stone can hit 1.5.
Is river rock better than mulch?
It lasts, but it does not feed the soil and it holds heat, so it suits foundation beds, drainage and xeric plantings rather than vegetable or annual beds. It is also permanent in practice: a 3 in bed over 300 sq ft is about 3.75 tons to shovel out if you change your mind.
Sources and references
- Construction aggregates calculator (volume to tons) (Vulcan Materials)
- CMG GardenNotes #245 Mulching (rock mulch, stone size and weed fabric) (Colorado State University Extension)
- C075 Guide to Mulches (mineral mulches reflect heat; fabric under rock) (Washington State University Extension)
Next steps for this project
The usual order for a landscaping & outdoor project. See all landscaping & outdoor calculators.
Results are estimates based on standard formulas and typical product specifications. Confirm quantities with your supplier and local code before ordering.