Calculating River Rock Coverage: How Much Stone Do You Need?

Volume-Based Calculation

Stone is sold by the cubic yard. One cubic yard spread 2 inches deep covers approximately 4.24 square yards (38.2 square feet).

Formula

Cubic yards needed = (Area in square feet × Depth in inches) ÷ 324

Example: A 200 sq ft bed at 2 inches deep = (200 × 2) ÷ 324 = 1.23 cubic yards. Order 1.5 yards to allow for settling.

Practical Tips

• Measure bed area accurately; break irregular shapes into rectangles.
• Confirm stone size with supplier—coverage varies slightly with gradation.
• Install landscape fabric underneath to reduce mixing with soil.
• Use edging to keep stone contained.