How much concrete needed for 12x30 slab?

To calculate the amount of concrete needed for a 12x30 slab, you first determine the area by multiplying the length (30 feet) by the width (12 feet), which equals 360 square feet. If the slab is to be 4 inches thick, convert the thickness to feet (4 inches = 1/3 feet) and then calculate the volume: 360 square feet x 1/3 feet = 120 cubic feet. Since there are 27 cubic feet in a cubic yard, divide 120 by 27 to find that approximately 4.44 cubic yards of concrete is needed.