Our inventory of salvaged corrugated metal tin is always changing. We sell all by the square foot. There are various widths from 24-30" wide and note each listing for allowed length ranges in the product description. Some of the product descriptions state how many square feet we consider each sheet. Other ones that have random lengths will be measured according to the the actual size- for example a sheet that is 2' wide and 10' long will be considered 20 square feet towards your total order. You will need to order extra square footage to compensate for waste, how much you overlap the seems, if you sort or discard because you don't like the reclaimed aspect or color combination.