Landscape Rock Calculator
Enter your project area, depth, and rock type
Your Results
* Add 10–15% overage for waste and uneven areas.
How We Calculate This +
Formula
Area × (Depth ÷ 12) ÷ 27 = Cu Yd · Cu Yd × Density = Tons
Key Assumptions
- Rock densities vary by type: river rock ~1.35 t/cu yd · lava rock ~0.65 · pea gravel ~1.40
- Add 10% for settling after installation
Price ranges based on national averages from HomeGuide, Angi, and LawnStarter. Updated May 2026.
How to Use the Rock Calculator
- 1 Enter your area dimensions — Measure the length and width of your project area in feet. For irregular areas, break them into rectangles and calculate each separately.
- 2 Set the depth — Use the quick-select chips (2", 3", or 4") or type a custom depth. Most landscape rock applications use 2–3 inches; drainage and pathways may need 4 inches.
- 3 Select your rock type — Each rock type has a different density, which affects how many tons you'll need. Lava rock is much lighter than river rock or decomposed granite.
- 4 Review your results — You'll see cubic yards, tons, bag count, and estimated cost. Add 10–15% extra when ordering to account for uneven areas and waste.
Landscape Rock Types Comparison
| Type | Price/cu yd | Weight/cu yd | Ideal Depth | Best For |
|---|---|---|---|---|
| Pea Gravel | $30–$55 | 2,800 lbs | 2–3" | Pathways, playgrounds, borders |
| River Rock | $45–$140 | 2,500 lbs | 2–4" | Garden beds, drainage, decorative |
| Lava Rock | $50–$180 | 1,300 lbs | 2–3" | Fire pits, beds, water features |
| Decomposed Granite | $30–$50 | 3,000 lbs | 2–4" | Paths, xeriscape, patios |
| Crushed Limestone | $40–$70 | 2,800 lbs | 3–4" | Driveways, base, drainage |
| Mexican Beach Pebbles | $150–$300 | 2,600 lbs | 2–3" | Water features, premium decorative |
Frequently Asked Questions
What is the difference between river rock and gravel? +
How deep should landscape rock be? +
Does landscape rock prevent weeds? +
How much does lava rock cost compared to river rock? +
How many tons of rock do I need for my yard? +
How Much Landscape Rock Do You Need?
Calculating the right amount of landscape rock saves you money and prevents a second trip to the supplier. The key variables are: area (sq ft), depth (inches), and rock type — because different rocks have very different densities.
Understanding Rock Weight and Coverage
Weight is what you actually pay for when buying bulk rock. A cubic yard of lava rock weighs just 1,300 lbs, while a cubic yard of decomposed granite weighs 3,000 lbs — more than twice as much. This means lava rock covers the same area at a fraction of the weight, making it surprisingly cost-competitive for large garden beds despite its higher per-ton price.
When buying bagged, most landscape rocks come in 0.5 cubic foot bags. At 3 inches deep, one cubic yard covers about 108 sq ft — that's 54 bags just for a small 10×10 garden bed. Bulk delivery typically costs 40–60% less per cubic yard than bagged material.
Choosing the Right Rock for Your Project
Pea gravel and decomposed granite are the best-value options for large areas and pathways. River rock works beautifully for drainage channels, dry creek beds, and accent borders. Lava rock excels in fire pit surrounds and low-water xeriscape gardens. Mexican beach pebbles deliver a premium look for water features and modern landscapes.
Always install landscape fabric beneath decorative rock to suppress weeds and keep the rock clean. Plan for a 10–15% overage in your order to cover uneven spots and edge fill.
Ready to calculate? Use the rock calculator above ↑ to get your exact cubic yards, tons, and cost in seconds.