weight of finished sheets = original plate weight - weight scraps punched down , the way to get the weight of scraps is to work out the open area firstly , Different pattern , different open area , above drawing showed the most common open area , net weight = Thickness x width x length x (100%-open area) ,for example 1mm x 1m x 1m size , 40% open, net weight is 1mm x 1m x 1m x 7.85 x (100%-40%) = 4.7kg.