Standard wheelbarrow tubs come in a variety of sizes, generally ranging from 2 cubic feet to 6 cubic feet in volume. Standard home and garden wheelbarrows are typically either 2 cubic feet (shallow tub) or 3 cubic feet (deeper tub), while a standard contractor-grade wheelbarrow tub measures about 6 cubic feet in volume.
The volume of a wheelbarrow can be found by measuring and then multiplying the length, width and height of the wheelbarrow basin. On the inside of the tub, measure from bottom to the top of the holding container for the depth, measure from the back of the tub to the point in the front of the wheelbarrow where the lip starts to rise to find the length, and measure from side to side for the width. This gives you a rough calculation, and from here you can either round up (to account for the front portion beginning at the lip) or run the same measurements for the front portion, beginning at the lip; multiply those three measurements. To account for the slope of the front, divide that number by 2, and add that to the initial volume calculated for the tub.
While a wheelbarrow's tub size is measured in cubic feet, materials such as mulch, soil and gravel are measured in cubic yards. One cubic yard of soil is equivalent to 27 cubic feet. Hauling 1 cubic yard of material in a 2-cubic-foot wheelbarrow requires 13 to 14 trips with the tub full. To haul that same cubic yardage of material in a 6-cubic-foot contractors-grade wheelbarrow takes four to five trips.