How to calculate river rock
Tons = Cubic yards × 1.35
River rock is smooth, rounded stone in mixed earthy colors. It's sold by the ton at landscape yards and in 0.5 ft³ bags at home centers. The right depth depends on the size of the stones: a good rule is about twice the diameter of a typical stone, so the soil or fabric underneath doesn't show through.
Worked example
A 25 × 2 ft border (50 sq ft) of medium river rock at 3 in deep: 50 × 3 ÷ 324 = 0.46 cubic yards. With 10% extra that's 0.51 cubic yards, about 0.69 tons, or 28 bags of 0.5 ft³.
River rock sizes and depths
| Size | Stone size | Depth | Coverage per ton |
|---|---|---|---|
| Small | ¾–1½ in | 2 in | about 120 sq ft |
| Medium | 1½–3 in | 3 in | about 80 sq ft |
| Large | 3–5 in | 4–5 in | about 50–60 sq ft |
Building a dry creek bed
A dry creek bed handles runoff and looks natural. Dig a shallow channel 6–12 in deep, wider than it is deep, and line it with landscape fabric. Use large rocks and a few boulders along the edges, then fill the center with medium and small river rock. Measure the channel's average width and length, and use the depth of rock you'll place, not the depth of the trench.
River rock vs mulch
River rock costs more up front but doesn't rot, blow away or need replacing every year. It's a good choice near downspouts, along foundations and in dry, sunny beds. It does hold heat, so it's harder on plants that like cool, moist roots, where mulch is the better option.
Frequently asked questions
How much area does a ton of river rock cover?
About 80 sq ft at 3 in deep, 120 sq ft at 2 in, and 50–60 sq ft at 4–5 in.
How many bags of river rock make a ton?
About 40 bags of 0.5 ft³. Bagged rock is handy for small areas, but bulk is much cheaper per ton.
Do I need landscape fabric under river rock?
Yes, in most cases. It stops weeds and keeps the rock from sinking into the soil. Use a woven, permeable fabric so water can drain.
How deep should river rock be?
About twice the size of the stones: 2 in for small rock, 3 in for medium and 4–5 in for large.
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Last reviewed 2026-11-14. Material weights are typical industry averages and vary by supplier, moisture and compaction.