How much landscape rock do I need?
Estimate landscape rock volume in cubic feet, cubic yards, and tons for gardens, pathways, and decorative beds.
Landscape rock calculator
Choosing the Right Landscape Rock
Landscape rock adds texture, color, and permanence to garden beds. Rock size, shape, and color should complement your landscape design and serve the intended function.
River Rock: Smooth, rounded stones available in sizes from 3/4 inch to 6 inches. River rock creates a natural creek-bed look and is excellent for drainage swales, dry streams, and decorative beds. Does not compact, so it is not suitable for walkways.
Crushed Granite / Decomposed Granite: Small, angular particles that compact into a stable, nearly solid surface. Ideal for pathways, driveways, and patio areas where you want a natural-looking but stable surface. Available in warm earthy tones.
Mexican Beach Pebbles: Small, smooth, dark river stones, typically 1 to 3 inches. Their polished appearance creates a striking contrast against greenery and mulched beds. Best for accent areas, succulent gardens, and around water features.
Lava Rock: Lightweight, porous volcanic rock in shades of red or black. Lava rock is excellent for fire pits, barbecue areas, and succulent gardens. It retains heat, resists weathering, and never fades.
Landscape Rock Cheat Sheet
Use this reference to choose the right rock for your landscape:
| Type | Best Used For | Size Range |
|---|---|---|
| River Rock | Dry creek beds, drainage, decorative beds, borders | 3/4" – 6" |
| Decomposed Granite | Pathways, driveways, patios, stable surfaces | 1/4" – 3/8" |
| Mexican Beach Pebbles | Accent beds, succulent gardens, water features | 1" – 3" |
| Lava Rock | Fire pits, barbecues, succulent beds, heat-retention areas | 1" – 4" |
Rock size and coverage
- Small rock (1/4 - 1/2 inch): 2-3 inches deep for pathways
- Medium rock (3/4 - 1 inch): 2-3 inches for garden beds
- Large rock (1-3 inches): 3-4 inches for decorative beds
- Boulders: Placed individually, not covered by this calculator
Larger rock leaves more air gaps, so you may need slightly more volume than the calculator shows. Adding 10% is recommended for larger rock sizes.
How to measure for landscape rock
Measure the length and width of the area in feet, then multiply to get square feet. Multiply the area by the desired depth (in feet) to get cubic feet, then divide by 27 for cubic yards. Landscape rock depth depends on the rock size — 2-3 inches for decorative gravel, 3-4 inches for medium rock, and 4-6 inches for large boulders. Add 10% extra for uneven ground and coverage gaps.
- Length × width: measure the bed dimensions in feet
- Depth: 2-3 inches for small decorative rock, 3-4 inches for medium, 4+ inches for large
- Weight conversion: cubic yards × 1.2-1.5 = approximate tons (varies by rock type)
- Waste: add 10% for slopes, curves, and uneven ground
Landscape rock installation tips
- Lay landscape fabric before adding rock — it prevents weeds and keeps rock from mixing with soil
- Edging is essential — use metal, plastic, or stone edging to keep rock contained and prevent migration
- Spread rock evenly using a rake — work from the edges inward for consistent depth
- For slopes, use heavier rock sizes (3+ inches) that resist sliding and erosion
- Avoid placing rock against house foundations — keep a 3-4 inch gap for drainage and pest inspection
Landscape rock vs. mulch
Both rock and mulch serve as ground cover, but they have different strengths. Mulch is better for garden beds and planting areas because it decomposes and improves soil health. Rock is better for pathways, drainage areas, and low-maintenance landscaping because it doesn't decompose or need replacement. Rock lasts indefinitely but doesn't benefit the soil, while mulch needs annual replacement but feeds the soil as it breaks down.
- Mulch: best for garden beds, around trees, and planting areas — improves soil over time
- Rock: best for pathways, drainage, and low-maintenance areas — lasts forever but doesn't improve soil
- Cost: mulch is cheaper upfront but needs annual replacement; rock costs more but is permanent
- Appearance: mulch gives a natural look; rock offers a clean, modern appearance
Worked example
For example, for a 12×8 ft decorative bed, 3 inches deep:
- Area = 12 × 8 = 96 sq ft
- Volume = 96 × (3 ÷ 12) = 24 cu ft
- Cubic yards = 24 ÷ 27 = 0.89 yd³
- Weight = 0.89 × 1.25 = 1.11 tons
- Order 1.25 tons to have extra for coverage gaps
Common mistakes
| Mistake | Why it matters |
|---|---|
| Not using landscape fabric | Weed barrier fabric under rock prevents weeds from growing through |
| Going too shallow | 2 inches minimum for decorative rock; less than 2 inches and the ground shows through |
| Mixing rock types in the same bed | Different colors/sizes in the same bed look messy — stick to one rock type |
Frequently asked questions about landscape rock estimates
How deep should landscape rock be?
Apply 2 to 3 inches for decorative garden beds. Use 3 to 4 inches for pathways and 4 to 6 inches for driveways.
How much does landscape rock weigh per cubic yard?
Most decorative landscape rock weighs 1.25 to 1.5 tons per cubic yard depending on rock type and size.
Should I use landscape fabric under rock?
Yes. Landscape fabric prevents weeds from growing through the rock and keeps the rock from mixing into the soil over time.