Multiply length × width × depth in feet, divide by 27 for cubic yards, then multiply by 1.5 to get tons of river rock. Use 2 inches of depth for small (1-inch) stones and 3–4 inches for larger 2–4 inch rock so the ground never shows through.
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River Rock Calculator Guide
River rock is the decorative heavyweight of landscape stone — smooth, water-polished stones from 3/4 inch up to 5 inches and beyond, used for dry creek beds, drainage swales, downspout runouts, and beds that need to look good for a decade with zero maintenance. This calculator estimates cubic yards and tons at 1.5 tons per cubic yard, the standard figure for washed river stone.
Because river rock is usually bought for looks, the estimating trap is different from other stone: coverage depends heavily on stone size. Big stones need a deeper layer to hide the ground beneath them, so a ton of 4-inch rock covers barely half the area of a ton of 1-inch rock.
River Rock Coverage by Stone Size
| Stone size | Minimum depth | One ton covers |
|---|---|---|
| 3/4–1 inch | 2 in | ≈ 90–100 sq ft |
| 1–3 inch | 3 in | ≈ 65–75 sq ft |
| 3–5 inch | 4 in | ≈ 50–60 sq ft |
| 5+ inch accent | single layer | ≈ 40–50 sq ft |
Set the calculator’s depth to match your stone size using the table, and the tonnage takes care of itself. Mixing two adjacent sizes — say 1-inch with 2–3 inch — locks the layer together and looks more like a natural stream bed than any single size.
Building a Dry Creek Bed That Actually Drains
A dry creek bed is drainage infrastructure dressed as decoration. Dig a shallow swale along the natural water path, line it with woven landscape fabric, then place stone in layers: large 3–5 inch rock anchoring the outer edges, medium stone filling the channel, and a few oversized boulders part-buried at bends — nature never drops a boulder on the surface. Water should enter at the high end and have somewhere legitimate to go at the low end: a drain, a rain garden, or daylight at the curb.
Always lay fabric first — river rock over bare soil sinks a little every wet season until the bed becomes a rock-studded mud strip. And for high-flow paths, step up stone size: moving water shifts 1-inch rock surprisingly easily. For the drainage layer around pipes themselves, washed angular stone grips better — see the #57 stone calculator.
Frequently Asked Questions
How much area does a ton of river rock cover?
At 2 inches deep, a ton of river rock covers roughly 90–100 square feet. Larger 3–5 inch stones need a deeper layer, so expect closer to 50–60 square feet per ton for big decorative rock.
What size river rock should I use?
Use 3/4–1 inch rock for ground cover and paths, 1–3 inch for dry creek beds and drainage swales, and 3–5 inch as accent stone. Mixing two sizes looks natural and locks the layer together better than a single size.
Should I put landscape fabric under river rock?
Yes — a woven landscape fabric stops the rock sinking into soil and keeps weeds from rooting up through the bed, while still letting water drain. Skip plastic sheeting, which traps water and kills nearby roots.
Is river rock good for drainage?
Excellent. Its rounded, washed stones leave large voids that move water fast, which is why river rock is the standard choice for dry creek beds, downspout runouts, and French drain surrounds.