How much river rock you need
Calculate the volume from area and depth: cubic yards = length × width × (depth in inches ÷ 12) ÷ 27. A 20 ft × 10 ft bed at 2 inches deep is about 1.23 cubic yards, roughly 1.67 tons at typical river-rock density (about 1.35 tons per cubic yard). For a cheaper base or drainage layer, use the gravel calculator.
How to use this calculator
Enter the bed length and width in feet and the depth in inches. The result shows cubic yards, tons, and cubic feet. For decorative ground cover, 2 inches is common; for areas where you want full coverage with no soil showing, go 3 inches. Bark and wood alternatives are covered by the mulch calculator.
Coverage by stone size
Larger river rock leaves more gaps and covers less area per cubic yard, so size up your depth for bigger stones. As a rough guide, one cubic yard at 2 inches deep covers about 160 square feet; at 3 inches, about 110 square feet. Bulk orders are placed by the yard, which the square feet to cubic yards calculator gives.
Use landscape fabric underneath
Lay landscape fabric under decorative rock to block weeds and stop the stone from sinking into the soil. Order about 5–10% extra rock for spread and settling. For a finer base or joint filler, see the sand calculator.
Rock is heavy and awkward to move by hand: a single cubic yard weighs well over a ton, so plan the drop-off point close to the bed and allow for a lot of wheelbarrow runs.
Frequently asked questions
- How much river rock do I need?
- Multiply length × width × depth in feet for cubic feet, divide by 27 for cubic yards, then multiply by about 1.35 for tons.
- How much area does a cubic yard of river rock cover?
- About 160 square feet at 2 inches deep, or 110 square feet at 3 inches.
- How deep should river rock be?
- About 2 inches for decorative cover, or 3 inches if you want full coverage with no soil visible, especially with larger stones.
- How many tons is a cubic yard of river rock?
- Roughly 1.35 tons, though it varies with stone size and moisture. Confirm with your supplier.
- Do I need edging around river rock?
- Yes for most beds. Without a hard edge the stone migrates into lawns and paths, where it damages mowers and looks untidy. Steel, stone or plastic edging all work as long as it stands proud of the rock.