Guides
How Much River Rock for a Landscape Border?
Quick Answer
For a landscape border that is 2 feet wide, 40 feet long, and 3 inches deep, you need about 20 cubic feet, or 0.74 cubic yards, of river rock. Using an estimated density of 1.35 tons per cubic yard, that equals about 1.0 ton, or about 1.1 tons with 10% extra.
Project Assumptions
This border example uses a simple rectangular strip calculation.
- Border width: 2 ft
- Border length: 40 ft
- Total area: 80 square feet
- Rock depth: 3 inches
- Material type: river rock
- Density estimate: 1.35 tons per cubic yard
- Extra material allowance: 10%
Step-by-step Calculation
Area = 2 x 40 = 80 sq ft. Depth = 3 / 12 = 0.25 ft.
Cubic feet = 80 x 0.25 = 20 cu ft. Cubic yards = 20 / 27 = 0.74 cu yd.
Tons = 0.74 x 1.35 = 1.0 ton. With 10% extra, plan for about 0.81 cu yd and about 1.1 tons.
Practical Buying Notes
River rock is often used for decorative borders, drainage areas, and low-maintenance landscape beds.
It is heavier than mulch and more permanent, so edge planning matters. For curved borders, measure the total length carefully and add extra material.
Common Mistakes
Rock borders need enough depth, edge control, and weed planning.
- Not using edging.
- Making the layer too shallow.
- Ignoring weed control below the rock.
- Underestimating curved borders.
- Assuming river rock and pea gravel cover the same way.
| Item | Estimate |
|---|---|
| Area | 80 sq ft |
| Depth | 3 inches |
| Volume | 20 cu ft |
| Cubic yards | 0.74 cu yd |
| Estimated tons | 1.0 ton |
| Cubic yards with 10% extra | 0.81 cu yd |
| Tons with 10% extra | 1.1 tons |
Related Calculator
Planning toolGravel CalculatorUse river rock density to estimate cubic yards and tons.FAQ
How deep should river rock be for a border?+
Around 2-3 inches is common for decorative coverage, depending on stone size and the surface below.
How many tons of river rock do I need for this example?+
About 1.0 ton, or about 1.1 tons with 10% extra.
Is river rock better than mulch?+
River rock lasts longer and does not decompose, while mulch improves soil over time. The better option depends on the project.