Pick the size of river rock you want and the calculator sets a typical depth for it. Enter your area to get cubic yards, tons and bags.
Extra to cover gaps and cost
Weights are typical for dry, loose material. Your supplier's figure may differ slightly.
Why rock size changes the depth
A layer of river rock needs to be deep enough to hide the ground or fabric underneath. Small stones do that in a thin layer, but bigger rocks leave large gaps, so the layer has to be roughly as deep as the rocks are big. That’s why the calculator changes the depth when you change the size.
| Rock size | Typical depth | 1 ton covers about | Good for |
|---|---|---|---|
| Small, ¾–1½ in | 2 in | 120 sq ft | Beds around plants, borders, paths |
| Medium, 1–3 in | 3 in | 80 sq ft | Beds, around downspouts, dry creek centers |
| Large, 3–5 in | 5 in | 50 sq ft | Dry creek banks, slopes, drainage areas |
| Cobbles, 5–8 in | 8 in | 31 sq ft | Creek edges and accents, usually one layer |
Coverage uses a typical weight of 1.30 to 1.35 tons per cubic yard, with no extra added.
Worked example
An 8 ft × 12 ft bed in medium river rock, 3 inches deep:
- 8 × 12 = 96 square feet
- 96 × 3 ÷ 12 = 24 cubic feet, or 0.89 cubic yards
- With 5 percent extra to cover gaps: 0.93 cubic yards
- 0.93 × 1.35 = about 1.26 tons, or 51 bags of 0.5 cubic feet
Where river rock works well
- Dry creek beds: use large rock and cobbles along the banks and smaller rock down the middle. Mixing sizes looks more natural than a single size.
- Under downspouts: a pad of medium rock stops the water digging a hole in the soil.
- Instead of mulch: river rock doesn’t rot or blow away, so it doesn’t need topping up every year.
- Next to the house: a strip of rock along the foundation keeps soil from splashing onto walls when it rains.
River rock or mulch?
River rock lasts for years and doesn’t wash away easily. Mulch breaks down and feeds the soil, which plants like, and it keeps roots cooler. Rock heats up in full sun and is hard work to remove later, so many gardeners use rock in drainage spots and mulch in planting beds.
Tips before you order
- Lay landscape fabric first. It slows weeds and stops the rock sinking into the soil over time.
- Colors vary a lot between quarries and regions. Ask to see a sample or a photo of the actual pile.
- Small sizes are often sold in 0.5 cubic foot bags. Large rock and cobbles are usually sold by the ton.
Frequently asked questions
How much river rock do I need for a 10 × 10 area?
At 2 inches deep, a 100 square foot area needs about 0.62 cubic yards, or 0.83 tons. At 3 inches, it needs about 0.93 cubic yards, or 1.25 tons.
How many square feet does a ton of river rock cover?
About 120 square feet at 2 inches deep and 80 square feet at 3 inches. Larger rock needs a deeper layer, so a ton covers less.
How deep should river rock be?
As a rule of thumb, at least as deep as the rocks are big: about 2 inches for small rock, 3 inches for medium and 5 inches or more for large.
Do I need landscape fabric under river rock?
It’s strongly recommended. Without it, weeds grow through and the rock slowly sinks into the soil.
How many bags of river rock make a ton?
About 40 bags of 0.5 cubic feet, based on 1.35 tons per cubic yard.
Results are estimates for planning. Weights are typical for dry, loose material. See How We Calculate for the formulas and values we use.