Granite tiles come in varying thicknesses, so the weight of a square foot will depend on which thickness is right for the job at hand.
The most common granite tiles and slabs are .75 inch and 1.25 inches thick. A square foot of the thinner variety weighs 12.8 pounds, and a square foot of the thicker variety weighs 18 pounds.
Professional moving equipment is extremely important to safely load and unload large quantities of granite. Even when lifting and placing individual slabs or tiles there is a risk of personal injury, so be sure to keep your back straight and lift with your legs.