How much red lava rock for 140 sq ft 2 inches deep?

To calculate the amount of red lava rock needed for 140 square feet at a depth of 2 inches, first convert the depth to feet: 2 inches is approximately 0.167 feet. Multiply the area by the depth: 140 sq ft x 0.167 ft = 23.38 cubic feet. Since lava rock is typically sold by the cubic yard, convert cubic feet to cubic yards by dividing by 27, resulting in about 0.87 cubic yards needed.