River Rock Calculator

One cubic yard of naturally rounded river rock weighs between 2,500 and 2,700 pounds (approximately 1.25 to 1.35 US tons), depending on stone gradation and moisture content. Smaller 3/8" to 3/4" pea gravel packs more densely (~2,700 lbs/yd³), while larger 3" to 5" cobbles have larger air voids (~2,500 lbs/yd³).

As a rule of thumb, layer depth must be at least twice the maximum stone diameter to prevent bare ground patches from showing through. For 3/8" to 3/4" river pebbles, use a 2-inch depth. For 1" to 3" river rock, use a 3 to 4-inch depth. For large 3" to 5" cobbles, install a 5 to 6-inch layer.

First, calculate cubic feet: Volume (cu ft) = Length (ft) x Width (ft) x (Depth (in) / 12). Convert to cubic yards by dividing by 27: Cubic Yards = Volume (cu ft) / 27. Finally, multiply cubic yards by 1.30 (average tons per cubic yard) and add 10% for ground settling: Total Tons = Cubic Yards x 1.30 x 1.10.

There are 27 cubic feet in one cubic yard. Therefore, it takes exactly 54 bags of 0.5 cubic foot river rock to equal one cubic yard (54 x 0.5 = 27 cu ft). If each 0.5 cu ft bag weighs approximately 45 to 50 lbs, 54 bags weigh roughly 2,500 to 2,700 lbs (1.3 tons).

Yes, installing heavy-duty commercial woven geotextile landscape fabric underneath river rock is strongly recommended. The fabric acts as a physical barrier that stops heavy stones from sinking into wet native soil over time and suppresses weed seed germination from the subgrade while allowing rain to freely drain.