How much concrete do you need to fill a 12 in hole 18 in deep?

To calculate the amount of concrete needed to fill a 12-inch diameter hole that is 18 inches deep, first convert the measurements to feet: the diameter is 1 foot and the depth is 1.5 feet. The volume of a cylinder is given by the formula V = πr²h. The radius (r) is 0.5 feet, so the volume is approximately π(0.5)²(1.5) = about 1.18 cubic feet. Thus, you would need roughly 1.18 cubic feet of concrete to fill the hole.