How much river rock do I need?
Tons = length × width × depth (ft) ÷ 27 × tons per cubic yard
A 10 × 10 ft bed at 3 inches is 25 cubic feet, about 0.93 cubic yards. River rock weighs about 1.35 tons per yard, so that is 1.25 tons. Lava rock is far lighter, about 0.5 tons per yard, so the same bed takes under half a ton.
How deep should landscape rock be?
| Rock size | Depth |
|---|---|
| Pea gravel, decomposed granite (under 1/2 in) | 2 to 3 in |
| 3/4 to 1-1/2 in river rock | 2 to 3 in |
| 1 to 3 in river rock | 3 to 4 in |
| 3 to 5 in cobble | 4 to 6 in |
A good rule is a depth of about twice the size of the largest stones, so no fabric shows through.
Typical depths and coverage for landscape rock
How deep to lay landscape rock depends on the job, so treat these depths as common starting points and defer to your plans or the product label. Coverage is how much ground one cubic yard of landscape rock, or one ton, spreads at that depth.
| Project | Depth | 1 cubic yard covers | 1 ton covers |
|---|---|---|---|
| Decorative bed | 2 in | 162 sq ft | 120 sq ft |
| Ground cover around plants | 3 in | 108 sq ft | 80 sq ft |
| Dry creek bed | 4 in | 81 sq ft | 60 sq ft |
| Base rock under a path or patio | 4 in | 81 sq ft | 60 sq ft |
| Erosion control | 6 in | 54 sq ft | 40 sq ft |
Three worked landscape rock jobs
Each job below adds 10% to the landscape rock volume for settling and spills, and converts to tons at 1.35 tons per cubic yard.
| Job | Size | Cubic yards | With 10% extra | Tons to order |
|---|---|---|---|---|
| Decorative bed | 20 × 5 ft at 3 in | 0.93 | 1.02 | 1.4 |
| Dry creek bed | 20 × 3 ft at 4 in | 0.74 | 0.81 | 1.1 |
| Side yard cover | 30 × 8 ft at 3 in | 2.22 | 2.44 | 3.3 |
Before you order landscape rock
- Rock sizes are sold by name, such as 3/4 inch, 1 to 2 inch and river rock. Larger rock leaves bigger gaps, so it covers a little less.
- Lighter rock, such as lava rock, weighs far less per yard than river rock, so use the right density.
- A landscape fabric under the rock slows weeds and keeps the rock from sinking into soil.
- A truck can usually dump the load at your driveway. Plan how you will move it to the bed.
Frequently asked questions
How much does a ton of river rock cover?
About 80 sq ft at 3 inches deep, or about 120 sq ft at 2 inches.
How much does a yard of river rock weigh?
About 1.3 to 1.4 tons, depending on stone size and moisture.
Is lava rock lighter than river rock?
Yes, much lighter. Lava rock is about 0.5 tons per cubic yard, so one ton covers roughly 2.5 times the area of river rock at the same depth.
How do I calculate tons of landscape rock?
Find cubic yards from length, width and depth, then multiply by the rock's tons per yard. A 100 sq ft bed 3 inches deep is 0.93 cubic yards, or about 1.4 tons of river rock at 1.35 tons per yard with 10% extra.
How much rock do I need for a dry creek bed?
Rock beds are often 3 to 4 inches deep, deeper in the channel. A 20 by 3 ft bed 4 inches deep is 0.74 cubic yards, before extra.
Reference charts
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