Landscape Rock Calculator: Free Online Decorative Stone Estimator
Use our free landscape rock calculator to determine exactly how much decorative stone you need for garden beds, xeriscaping, water features, borders, and hardscape accents. Designed for landscape architects, professional landscapers, and homeowners, this tool calculates the cubic yards and tons of decorative rock required based on your area dimensions, rock type, and desired depth. Choose from river rock, crushed granite, lava rock, pea gravel, or Mexican beach pebbles to get accurate, project-specific estimates instantly.
How to use this calculator.
- Select your rock type. Choose from the available decorative rock options using the dropdown. Each rock type has a different density and aesthetic, affecting both the weight calculation and the visual result. River rock is smooth and rounded; crushed granite is angular and locks together; lava rock is lightweight and porous.
- Enter your bed dimensions. Input the length and width of your landscape bed in feet. For curved or irregular beds, break the area into approximate rectangles, calculate each separately, and sum the results.
- Set your rock depth. For decorative ground cover, 2-3 inches is standard and cost-effective. Deeper depths (3-4 inches) provide better weed suppression and a more luxurious appearance but increase material cost proportionally. Enter depth in inches.
- Review your material quantities. The calculator displays coverage area, volume in cubic yards, and weight in tons: the standard ordering units at landscape supply yards and quarries.
How do you calculate landscape rock quantity for ground cover?
Landscape rock quantity is calculated by multiplying the area by the depth, converting to cubic yards, and then to tons using the selected rock type's density.
Area (sq ft) = Length (ft) × Width (ft)
Volume (cu yd) = Area × Depth (in) ÷ 324
Weight (tons) = Volume (cu yd) × Rock Density (lbs/cu yd) ÷ 2,000
Where:
- 324 is the standard conversion factor for converting square-feet-area × inches-depth to cubic yards. Derived from 12 inches per foot × 27 cubic feet per cubic yard.
- River rock (3-5 inch): approximately 2,600 lbs/cu yd. Smooth, rounded stones ideal for dry creek beds and drainage swales.
- Crushed granite: approximately 2,700 lbs/cu yd. Angular, interlocking stone perfect for pathways and driveways.
- Lava rock: approximately 1,600 lbs/cu yd. Lightweight, porous volcanic rock excellent for mulch replacement and xeriscaping. Lava rock covers approximately 60% more area per ton than granite.
- Pea gravel: approximately 2,400 lbs/cu yd. Small, smooth, pea-sized stones for patios and play areas.
Example calculation.
Let's calculate the landscape rock needed for a front yard xeriscape bed.
Scenario: You are converting a 25 ft × 15 ft front yard section to a low-water landscape using 3 inches of crushed granite.
- Calculate the area: 25 ft × 15 ft = 375 sq ft
- Calculate the volume: 375 × 3 ÷ 324 = 3.47 cu yd
- Calculate the weight: 3.47 × 2,700 ÷ 2,000 = 4.68 tons
- Add 10% waste factor: 4.68 × 1.10 = 5.15 tons
- Order quantity: Round up to 5.5 tons. This is a partial truckload: verify the minimum delivery quantity with your local supplier (typically 3-5 tons minimum for delivery).
Result: You need approximately 5.5 tons of crushed granite for this 375-square-foot xeriscape bed. The 3-inch depth provides excellent weed suppression and a clean, professional appearance. Install over landscape fabric for best long-term results.
Tips from the field.
- Lava rock is half the weight of granite. If your project involves manual handling (wheelbarrowing rock to a backyard with no equipment access), lava rock dramatically reduces the labor. Five tons of granite is approximately 125 wheelbarrow loads. The same coverage in lava rock is about 75 loads: a significant labor savings.
- Install 4-6 inch steel edging for rock beds. Decorative rock migrates downhill and outward over time from rain, wind, and foot traffic. Steel edging 4-6 inches tall, buried 3-4 inches deep with 1-2 inches exposed, contains the rock and provides a crisp separation between rock beds and lawn or planting areas.
- Consider your climate when choosing rock color. Dark- colored rocks (black lava, dark river rock) absorb heat and can raise soil temperatures by 10-15°F, stressing plants in hot climates. Light- colored rocks (white marble chips, tan crushed granite) reflect heat and keep root zones cooler. In desert climates, choose light colors. In cool climates, dark rocks can extend the growing season by warming the soil.
- Rinse bulk rock before spreading. Quarry-fresh bulk rock is covered in stone dust that clouds rainwater runoff and dulls the color. Spread the rock on a tarp and hose it down, or spread it in place and let the first rain wash it clean. Pre-washed bagged rock from home centers costs 3-5 times more than bulk but requires no rinsing.
- For slopes, use angular crushed stone, not rounded rock.Rounded rock (river rock, pea gravel, beach pebbles) rolls downhill on slopes greater than 5%. Angular crushed stone locks together and stays in place on slopes up to 20%. For slopes steeper than 20%, use a cellular confinement system (geocell) filled with angular stone to prevent migration.
Disclaimer: This calculator provides estimates for planning purposes only. Actual material requirements vary based on subgrade preparation, rock size distribution, compaction, and installation technique. Rock color and size may vary from quarry samples due to natural geological variation. PavementCalculator.com assumes no liability for material overages, shortages, or aesthetic dissatisfaction.
Cost, price, and density figures on this page reflect approximate U.S. averages as of August 2026 and vary by region, supplier, and material availability.
Frequently asked questions.
How much landscape rock do I need?
Measure the area (length × width in feet) and multiply by the desired depth (in inches ÷ 12) to get cubic feet, then divide by 27 for cubic yards. For example: a 100 sq ft bed at 3 inches deep = 100 × (3÷12) = 25 cu ft ÷ 27 = 0.93 cu yd. One cubic yard of landscape rock covers approximately 108 sq ft at 3 inches deep, or 81 sq ft at 4 inches. For ground cover, 2-3 inches is standard; for pathways, 3-4 inches.
How many square feet does a ton of landscape rock cover?
Coverage varies by rock size and depth. At 2-3 inches deep, one ton covers: Large river rock (3-5 inch): 50-70 sq ft. Medium river rock (1-3 inch): 60-80 sq ft. Pea gravel (3/8 inch): 80-100 sq ft. Crushed decorative stone (1/2-1 inch): 70-90 sq ft. Lava rock (1-2 inch): 90-110 sq ft (lighter weight). These are approximate: the exact coverage depends on rock density and installation depth. Use our calculator for precise estimates.
What depth should landscape rock be?
For weed suppression and ground cover: 2-3 inches minimum. For pathways: 3-4 inches. For driveways: 4-6 inches of crushed stone. Mulch areas: 2-4 inches. Around plants and trees: 2-3 inches, keeping rock away from the stem/trunk. Deeper than 4 inches rarely provides additional benefit and adds unnecessary cost. Under landscape fabric, 2 inches may suffice for decoration only (non-traffic areas).
Should I use landscape fabric under rock?
Yes, landscape fabric (geotextile) is strongly recommended under decorative rock. It: (1) Prevents weeds from growing through the rock: fabric blocks light while allowing water. (2) Prevents the rock from sinking into the soil over time. (3) Makes future removal easier if you change landscaping. Use commercial-grade non-woven geotextile fabric, NOT thin weed barrier plastic. Overlap seams by 6-12 inches and secure with landscape staples every 2-3 feet. Fabric adds $0.15-$0.30/sq ft to project cost but saves years of maintenance.
How much does landscape rock cost?
Bulk landscape rock: $40-$150 per cubic yard depending on type. Pea gravel: $35-$55/yard. River rock (medium): $80-$140/yard. Mexican beach pebbles: $200-$400/yard. Lava rock: $50-$90/yard. Bagged rock (0.5 cu ft bags): $4-$12 per bag, which is 2-3× more expensive than bulk. Delivery fees: $50-$150 per truckload. For a 200 sq ft area at 3 inches deep (1.85 cu yd): bulk cost = $75-$275 for materials.
What size landscape rock should I use?
Pea gravel (3/8 inch): Best for pathways, patios, dog runs: smooth and comfortable underfoot. 1-2 inch rock: Ideal for general ground cover, drainage areas, and borders. 2-4 inch rock: Good for dry creek beds, accent areas, and large coverage areas. 4+ inch boulders: Statement pieces, retaining walls, and water features. For pathways you walk on, use 3/8-3/4 inch angular stone: it compacts and stays in place better than rounded rock.
How much landscape rock do I need per square foot?
At a 2-inch depth, you need approximately 0.0062 cubic yards or 16 pounds (0.008 tons) of landscape rock per square foot for standard-density rocks like river rock or granite. At 3 inches: 0.0093 cubic yards or 24 pounds (0.012 tons) per square foot. At 4 inches: 0.0123 cubic yards or 32 pounds (0.016 tons) per square foot. Lava rock requires approximately 40% less weight per square foot due to its lower density.
What is the best landscape rock for weed control?
For maximum weed suppression, crushed stone (angular) at 3-4 inches depth over quality landscape fabric is most effective. The angular particles interlock tightly, leaving fewer gaps for weed seeds to reach the soil. Rounded rocks (river rock, pea gravel) leave more gaps between stones where weed seeds can settle and germinate. Regardless of rock type, landscape fabric underneath and a minimum 3-inch depth are the two most important factors for weed control.
Is landscape rock cheaper than mulch in the long run?
Landscape rock costs $60-$200 per ton installed versus $30-$50 per cubic yard for mulch. However, rock lasts indefinitely (decades) while mulch must be replenished every 1-3 years. Over 10 years, rock is typically 30-50% cheaper than mulch despite the higher upfront cost. The break-even point is approximately 3-5 years. Rock is also more fire-resistant than mulch, making it the safer choice in wildfire-prone areas.
How do I calculate rock for a circular bed?
For a circular bed, measure the diameter (the distance across the circle through the center). The formula is: Area = 3.14159 × (Diameter ÷ 2) squared. Or use the shortcut: Area = Diameter × Diameter × 0.7854. For example, a 12-foot circular bed: 12 × 12 × 0.7854 = 113.1 square feet. Then enter this area as length × width (e.g., 12 ft × 9.4 ft) into the calculator, or calculate the volume directly: 113.1 × depth in inches ÷ 324 = cubic yards.
Can I put landscape rock directly on soil?
You can, but it is not recommended for long-term applications. Without landscape fabric, the rock gradually sinks into the soil (especially in clay soils during wet periods), weeds grow through from below, and soil mixes with the rock, creating a messy appearance. Landscape fabric is an inexpensive barrier ($0.15-$0.40 per square foot) that prevents these problems and extends the functional life of your rock installation from 2-3 years to 15-20+ years.