Area to volume to tonnage, in three steps
Coverage is length times width. Multiply by the depth (in feet) to get volume, then convert to tons by the rock's density. The one conversion people forget is turning the depth from inches into feet before multiplying.
What one cubic yard covers, by depth
Rock is sold by the cubic yard or ton, but you measure your yard in square feet. This is the crossover: how far a single cubic yard spreads at each common depth.
| Depth | Coverage per yd³ | Typical use |
|---|---|---|
| 1″ | 324 sq ft | Top-up layer |
| 2″ | 162 sq ft | Decorative |
| 3″ | 108 sq ft | Decorative |
| 4″ | 81 sq ft | Drainage |
| 6″ | 54 sq ft | Dry creek bed |
A 10 × 12 ft patio (120 sq ft) at 3″ needs about 1.1 cubic yards, which is roughly 1.5 tons before any waste allowance.
Density by stone size, plus the order buffer
- Small (1–2″). About 1.35 tons per cubic yard — the default most calculators use.
- Pea gravel and large stone. Smaller pea gravel runs lighter (~1.30), larger 5–12″ stone packs denser (~1.40). Pick the density for your grade before you order, or the weight is off.
- Add 10–15% waste. Spillage, settling and uneven ground eat into the calculated amount, so order a bit over rather than run short mid-project.
Common questions
How much river rock do I need per square foot?
One cubic yard covers 108 square feet at 3 inches deep, so a 3-inch layer takes about 0.0093 cubic yards, or roughly 25 pounds, per square foot. Deeper layers use proportionally more: double the depth and you double the material.
How many tons is a cubic yard of river rock?
About 1.35 tons for small-to-medium river rock, which is the usual figure. Larger stones pack denser at up to about 1.4 tons per cubic yard, and small pea gravel is a little lighter at around 1.3.
How deep should river rock be?
Two to three inches for a decorative surface, four to six inches for drainage, and six to eight inches for a dry creek bed. Going too shallow lets weeds through and leaves bare patches.
