How Much Landscape Rock Do I Need? Yards, Tons and Bags
Part of the project planner: Planning a new lawn and garden beds.
A 20 × 5 ft bed (100 ft²) covered 3 inches deep with river rock needs 1.02 cubic yards with 10% extra, which weighs about 1.32 tons. A cubic yard covers 108 ft² at that depth. The landscape rock calculator does your own bed, with the weight of the rock you choose.
Coverage by depth
No waste added. River rock at 1.3 tons per cubic yard:
| Depth | Area covered by 1 yd³ | Yards for 100 ft² | Tons for 100 ft² |
|---|---|---|---|
| 1 in | 324 ft² | 0.31 | 0.40 |
| 2 in | 162 ft² | 0.62 | 0.80 |
| 3 in | 108 ft² | 0.93 | 1.20 |
| 4 in | 81 ft² | 1.23 | 1.60 |
| 6 in | 54 ft² | 1.85 | 2.41 |
Rock for common beds
3 inches deep, 10% extra, river rock:
| Bed | Area | Cubic yards | Tons | Bags of 0.5 ft³ |
|---|---|---|---|---|
| 10 × 4 ft | 40 ft² | 0.41 | 0.53 | 22 |
| 20 × 5 ft | 100 ft² | 1.02 | 1.32 | 55 |
| 30 × 6 ft | 180 ft² | 1.83 | 2.38 | 99 |
| 40 × 8 ft | 320 ft² | 3.26 | 4.24 | 176 |
Weights of different rocks
Per cubic yard, which changes the tons to order. Lava rock at 0.9 tons a yard would make the 100 ft² bed 0.92 tons instead of 1.32. See the cubic yards to tons chart for more.
How to lay it
- Mark the bed and dig out about the depth of the rock, so the surface does not sit above the lawn or the path.
- Slope the ground slightly away from the house, and edge the bed with steel, plastic or stone.
- Lay landscape fabric over the soil, overlapping the seams. It keeps weeds down and stops the rock sinking.
- Spread the rock evenly with a rake, to the depth you planned.
- Do not pile it against siding or the foundation.
Mistakes to avoid
- Skipping the edging. Rock spreads onto the lawn, and the mower throws it.
- Using plastic sheeting instead of fabric. Water collects under it.
- Choosing small round rock for a path. Crushed stone packs and stays put.
- Forgetting that leaves and soil will settle on top, so you have to rake or blow it from time to time.
Estimates only: ask your supplier for the weight and the size of the rock you choose.
Frequently asked questions
How much river rock do I need for 100 square feet?
1.02 cubic yards (1.32 tons) at 3 inches deep with 10% extra. At 4 inches it is 1.36 yards.
How many square feet does a cubic yard of rock cover?
108 ft² at 3 inches deep, 162 ft² at 2 inches and 81 ft² at 4 inches, with no waste.
How deep should landscape rock be?
Two to three inches for decorative rock over fabric. Less looks thin and shows the soil, and more is heavy and hard to walk on.
How much does a cubic yard of river rock weigh?
About 1.3 tons (2,600 pounds). Lava rock is lighter, around 0.9 ton, and granite chips heavier. Ask your supplier.
Is it cheaper to buy rock in bags or in bulk?
Bulk is far cheaper once you need more than about half a yard. A 20 × 5 ft bed at 3 inches would need 55 bags of 0.5 ft³ against 1.02 cubic yards in bulk.
More guides
Tools & materials for this project
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Estimates only. Quantities depend on your materials, site and supplier. Confirm important numbers before you order, and follow local building codes for anything structural.