Need to find out how many slate per square? (A square is the equivalent of 100 square feet) Use the calculator below. The answer depends on the length and width of the slate, and also the headlap that is used when installing. The normal headlap is 3 inches, but this may need to be increased when installing on a lower slope roof. When calculating how much slate you’ll need for a project, don’t forget to add additional slates for waste!
How much does slate weigh per square? It depends on the size of the slate. On average, slate (measured at approximately 1/4 inch thick) weighs around 935 pounds per square.
Per square, smaller roofing slates actually weigh more than larger slates because more overlap is used.
Slate sizes can start as small as 6×12 inches and be as large as 16×24. (Some thicker slates can be much larger—and heavier!)
This calculator is also helpful for estimating the amount of slates that could be salvaged in a roof removal and for estimating weight of the slate removed for dumpster costs.
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