A slab is a flat, sheet-like section of natural or manufactured stone. A standard slab size is between 9 and 10 feet long by between 5 and 6 feet wide. A typical slab offers approximately 45 square feet. In terms of thickness, slabs are generally offered in 3/4" and 1 1/4" thicknesses. These can weight between 13 and 19 pounds per square foot.