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Landscaping & YardRiver Rock Calculator — How Much River Rock Do I Need?
Enter the area and depth to estimate decorative river rock in cubic yards and tons — for beds, dry creek borders, and around downspouts.
How this calculator works
Volume = area × depth, converted to cubic yards and to tons at about 1.4 tons per cubic yard. Larger stone leaves more air gaps, so weight varies.
What changes how much you need
- 2 inches covers decoratively; use 3–4 inches for paths or strong weed suppression.
- Bigger stones (2–4") need a deeper layer to fully hide the ground.
- Lay landscape fabric underneath to slow weeds and keep rock from sinking.
- River rock is heavy and hard to move — confirm delivery access.
- A cubic yard weighs about 2,400–2,800 lb, well past a half-ton pickup’s payload, so plan on delivery for anything over about half a yard.
River rock coverage per cubic yard and per ton, by depth
Coverage per cubic yard is fixed geometry (27 cubic feet ÷ your depth). Per-ton coverage shifts with stone size and moisture: bigger, rounder stone leaves larger voids and weighs less per yard — nearer 1.25–1.35 tons — so a ton of 2–4 inch cobble spreads a little further than a ton of 3⁄4-inch rock.
| Depth | Sq ft per cubic yard | Sq ft per ton (≈1.4 t/yd³) |
|---|---|---|
| 1 in | 324 sq ft | 230 sq ft |
| 2 in | 162 sq ft | 115 sq ft |
| 3 in | 108 sq ft | 77 sq ft |
| 4 in | 81 sq ft | 58 sq ft |
| 6 in | 54 sq ft | 39 sq ft |
Depth and use by river rock size
Rule of thumb: the layer wants to be roughly two to three times the stone’s diameter before it hides the ground and stays put. That is why large decorative cobble is hand-placed one stone deep rather than spread to a depth.
| Stone size | Recommended depth | Best for |
|---|---|---|
| 3⁄8–1⁄2 in | 2 in | Walkways, pet areas, tight borders, filling between pavers |
| 3⁄4–1 in | 2–3 in | Planting beds, tree rings, general ground cover |
| 1–2 in | 3 in | Beds where you want real weed suppression, downspout splash areas |
| 2–4 in | 4 in | Dry creek beds, drainage swales, erosion control on gentle slopes |
| 4–8 in (cobble) | Placed one stone deep | Creek-bed banks, accent groupings, armouring a French drain |
River rock needed by common project
Volumes are the finished layer, before the 10% the calculator adds for spreading loss and uneven ground.
| Project | Area | Depth | Cubic yards | ≈ Tons |
|---|---|---|---|---|
| Downspout splash pad · 4 × 4 ft | 16 sq ft | 3 in | 0.15 yd³ | 0.2 |
| Border bed · 15 × 4 ft | 60 sq ft | 2 in | 0.37 yd³ | 0.5 |
| Side-yard path · 30 × 3 ft | 90 sq ft | 3 in | 0.8 yd³ | 1.2 |
| Foundation drip strip · 60 × 2 ft | 120 sq ft | 3 in | 1.1 yd³ | 1.6 |
| Dry creek bed · 25 × 5 ft | 125 sq ft | 4 in | 1.5 yd³ | 2.2 |
| Large front bed · 30 × 10 ft | 300 sq ft | 2 in | 1.9 yd³ | 2.6 |
Frequently asked questions
How deep should river rock be?
About 2 inches for decorative beds, or 3–4 inches for pathways and stronger weed coverage.
How many tons of river rock in a yard?
Around 1.4 tons, varying with stone size and moisture.
Should I use fabric under river rock?
Yes — landscape fabric slows weeds and keeps the rock from working down into the soil over time.
How much area does a ton of river rock cover?
About 115 sq ft at 2 inches deep, 77 sq ft at 3 inches, and 58 sq ft at 4 inches, working from roughly 1.4 tons per cubic yard. Larger, rounder stone weighs less per yard, so a ton of 2–4 inch cobble stretches slightly further than a ton of 3⁄4-inch rock.
How much river rock do I need for a dry creek bed?
Plan 4 inches of 2–4 inch stone across the channel — a 25 × 5 ft bed works out to about 1.5 cubic yards, roughly 2.2 tons. Order the larger 4–8 inch bank cobble separately: it is hand-placed one stone deep, not spread to a depth, so it does not follow the volume math.
How much does a cubic yard of river rock weigh?
Roughly 2,400–2,800 lb — 1.2 to 1.4 tons — depending on stone size and how wet it is. That is well over a half-ton pickup’s payload for a single yard, which is why most people take a dump delivery rather than haul it themselves.
Will river rock stop weeds?
It slows them a lot but does not stop them. Wind-blown seed eventually germinates in the dust and leaf litter that collects between the stones. A 3-inch layer over landscape fabric suppresses far more than a 2-inch decorative scatter, and blowing the debris out once a season is what keeps it clean.
How wide should the rock strip along the house be?
A strip about 18–24 inches wide at 3 inches deep is typical for a drip edge under the eaves, graded to fall away from the wall. Keep the rock below the siding line and leave any weep holes clear so water can still escape.