Landscape Rock Calculator

The amount of landscape rock depends on three factors: the area to cover (length × width), the desired depth, and the rock type. A standard decorative rock bed uses 2-3 inches of depth. For a typical 200 square foot area at 3 inches deep, you would need approximately 0.93 tons of pea gravel or 0.97 tons of river rock. Use our calculator above to get an exact estimate for your specific project dimensions and preferred rock type.

For most decorative landscaping, 2-3 inches of rock depth is ideal. Smaller rocks like pea gravel work well at 2 inches, while larger river rocks (2-3 inch diameter) need 3-4 inches of depth for full ground coverage. For walkways and high-traffic areas, use 3-4 inches over a compacted base. Drainage applications like French drains require 6-12 inches of gravel. If using landscape fabric underneath, you can sometimes get away with slightly less depth as the fabric prevents rocks from sinking into soil.

The weight per cubic yard varies significantly by rock type. Pea gravel weighs approximately 1.30 tons per cubic yard, river rock about 1.35 tons, crushed granite about 1.28 tons, and lava rock only about 0.68 tons per cubic yard due to its porous structure. A standard rule of thumb is that most gravel and crushed stone products weigh between 1.2 and 1.5 tons per cubic yard when measured in their loose, bulk state. Always specify the rock type when ordering to ensure accurate weight estimates.

Buying rock in bulk (by the ton or cubic yard) from a landscape supply yard is almost always cheaper than purchasing bags from a retail store. Bulk rock typically costs $30-80 per ton for common varieties, while bagged rock at home improvement stores can cost the equivalent of $100-200 per ton when you calculate the per-unit price. However, bulk delivery usually requires a minimum order (often 1-3 tons) and delivery fees of $50-150. For very small projects under 50 square feet, bags may be more practical.

Pea gravel consists of small, rounded stones typically 1/8 to 3/8 inch in diameter with smooth edges. River rock is larger, ranging from 1 to 5 inches in diameter, and has been naturally rounded by water erosion. Pea gravel compacts more densely, works well for walkways and fills, and costs less per ton. River rock is better for decorative beds, around plants, and in dry creek beds where visual appeal is primary. River rock allows better water drainage than pea gravel due to larger gaps between stones.

Landscape fabric (weed barrier) is recommended under most decorative rock installations. It prevents weeds from growing up through the rocks and keeps the rocks from sinking into the soil over time. For best results, use commercial-grade woven landscape fabric (not the thin black plastic sheets), overlap seams by 6-12 inches, and secure with landscape staples every 12-18 inches. Note that organic debris will eventually accumulate on top of the fabric and support weed growth, so periodic maintenance is still needed.

For irregular or curved areas, divide the space into approximate rectangles, circles, or triangles and calculate each section separately, then add them together. For a circle, use the formula: area = π × radius². For a triangle: area = 0.5 × base × height. Alternatively, you can take the longest and widest measurements of the irregular area, calculate as if it were a rectangle, and then multiply by 0.8 to account for the irregular shape. Adding 5-10% extra material is wise for complex shapes.

Delivery fees for bulk landscape rock typically range from $50 to $150 depending on the distance from the supplier and the quantity ordered. Many landscape supply yards offer free delivery for orders over 5-10 tons. Standard delivery uses a dump truck that deposits the material in your driveway or as close to the project area as the truck can access. If your site has limited access, you may need a smaller truck or wheelbarrow transfer, which costs extra. Always confirm delivery details and site accessibility before ordering.

For drainage applications, angular crushed rock in the 3/4 to 1-1/2 inch range is ideal because the irregular shapes create consistent void spaces that allow water to flow freely. Crushed granite, limestone, and basalt are popular choices for French drains, dry wells, and foundation drainage. Avoid using round rocks like pea gravel or river rock for structural drainage as they shift and compact, reducing water flow over time. For best results, wrap drainage rock in geotextile fabric to prevent soil infiltration.