How to Calculate Landscape Rock
Landscape rock is sold by the cubic yard or ton. Calculate your area in square feet, choose your desired depth, and use the formula below to find how much you need. Most decorative rock beds look best at 2–3 inches deep — enough for full coverage without excessive weight.
Rock Formula:
Cubic Yards = (Area in sq ft × Depth in ft) ÷ 27
Tons = Cubic Yards × Stone Density (1.3–1.6)
Coverage by Rock Size
| Rock Size | 1 Ton Covers at 2" Deep | Best Use |
|---|
| 3/4" Pea Gravel | ~90 sq ft | Paths, playgrounds |
| 1" River Rock | ~80 sq ft | Beds, drainage |
| 2" River Rock | ~70 sq ft | Beds, borders |
| 3–5" River Rock | ~55 sq ft | Accents, dry creek beds |
| Decomposed Granite | ~100 sq ft | Paths, patios |
Landscape Rock Cost
| Rock Type | Cost per Ton |
|---|
| River Rock (small) | $45–$80 |
| River Rock (large) | $55–$100 |
| Decomposed Granite | $35–$65 |
| Lava Rock | $60–$100 |
| White Marble Chips | $80–$150 |
| Black Polished Rock | $100–$200 |
Frequently Asked Questions
How much landscape rock do I need for a 10×10 area?▾
At 2 inches deep, a 10×10 area (100 sq ft) needs about 0.62 cubic yards or roughly 0.9 tons. At 3 inches, you'd need 0.93 cubic yards or about 1.35 tons.
Is landscape rock better than mulch?▾
Rock is more permanent, doesn't decompose, and doesn't require annual replacement. However, it retains heat, can increase soil temperature in summer, and doesn't enrich the soil. Mulch is better for plant health; rock is better for low-maintenance, drought-tolerant plantings.
Do I need landscape fabric under rock?▾
Yes, strongly recommended. Without landscape fabric, weeds will grow up through rock, and the rock will slowly sink into the soil. Use a heavy-duty woven geotextile fabric, not the cheap black plastic — it allows water through while blocking weeds.
What size rock should I use for a dry creek bed?▾
Dry creek beds typically use a mix of sizes: 3–5 inch river rock for the 'stream' center, 1–2 inch rock for the edges, and occasional larger boulders (6–12 inches) for accents. Mixing sizes creates the most natural look.