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.
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 |