How this calculator works
Rock is the area times the depth, converted to cubic yards, with waste added. Weight is the cubic yards times the tons per cubic yard of the rock you choose. A cubic yard covers 324 square feet at 1 inch deep, so divide 324 by the depth in inches to find the area one yard will cover.
Worked example: a 20 × 5 ft bed (100 ft²) covered 3 inches deep with river rock needs 1.02 cubic yards with 10% extra, which weighs 1.32 tons and is 55 bags of 0.5 ft³. At 4 inches deep it is 1.36 yards. Lava rock at 0.9 tons a yard would weigh 0.92 tons.
How far does a cubic yard of rock go?
Square feet covered by one cubic yard, with the tons of river rock.
| Depth | Area per cubic yard | Tons of river rock per 100 ft² |
|---|---|---|
| 2 in | 162 ft² | 0.80 |
| 3 in | 108 ft² | 1.20 |
| 4 in | 81 ft² | 1.60 |
| 6 in | 54 ft² | 2.41 |
Tips before you buy
- Rock over fabric stays clean longer, but leaves and soil still settle on top: plan to rake or blow it.
- Use edging to hold the rock in, and slope it away from the house.
- Round rock moves underfoot, so use crushed stone for paths and round for decoration.
- Buy in bulk if the area is more than a few square feet, and have it dropped near the work.
- Do not pile rock against the siding or the foundation.
Tools & materials for this project
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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 2 inches it is 0.68 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?
2 to 3 inches for decorative rock over fabric. Less looks thin, 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 lb), and lava rock is lighter, around 0.6 to 1 ton. Ask your supplier.
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Related calculators & guides
Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.