How many bags of concrete for 10 x 10 slab?

To determine how many bags of concrete you need for a 10 x 10 slab, first calculate the volume: a 4-inch thick slab is 10 x 10 x (4/12) = 33.3 cubic feet. A typical 80-pound bag of concrete covers about 0.6 cubic feet. Dividing 33.3 by 0.6 means you would need approximately 56 bags of concrete for that size slab.