CALCULATION METHOD
How much river rock do I need?
Measure the area, choose a finished depth, and select the closest river rock size. The calculator finds cubic feet and cubic yards, then applies the editable bulk density to estimate pounds and short tons. It also divides the order volume by the labeled bag volume and rounds up to a whole bag.
Cubic feet = area × depth in feet
Cubic yards = cubic feet ÷ 27
Short tons = cubic feet × density ÷ 2,000
Bags = order cubic feet ÷ bag volume, rounded up
River rock calculation example
A 20 ft × 15 ft bed covered 2 inches deep has a net volume of 50 cubic feet. With 10% overage and river rock at 100 lb/ft³, the order is about 2.04 cubic yards or 2.75 short tons. Using 0.5 cu ft bags, the same volume requires 110 bags.
River rock coverage per ton
Using the 100 lb/ft³ preset, one short ton covers approximately 240 sq ft at 1 inch, 120 sq ft at 2 inches, 80 sq ft at 3 inches, or 60 sq ft at 4 inches. The live coverage result changes when you adjust density or depth.
| Finished depth | Coverage per short ton | Coverage per cubic yard |
|---|---|---|
| 1 inch | 240 sq ft | 324 sq ft |
| 2 inches | 120 sq ft | 162 sq ft |
| 3 inches | 80 sq ft | 108 sq ft |
| 4 inches | 60 sq ft | 81 sq ft |
How rock size changes the estimate
Rounded stones leave different void spaces as size and grading change. That affects loose bulk density and the weight delivered in each cubic yard. The size presets range from 92 to 100 lb/ft³ as planning assumptions; replace them with your stone yard’s value whenever possible.
Bulk river rock or bags?
Use the bag count for small projects and the ton or cubic-yard result when requesting a bulk quote. Bag coverage varies by product, so select the volume printed on the bag instead of relying on a generic weight conversion.
Inch Calculator river rock method and stone bulk-weight ranges. Accessed September 10, 2026.