That's a huge shed! Anyway, without taking into consideration that there will be windows and doors this is how you calculate: Length 32ft (each wall) x2= 64 Width 28ft (each wall ) x2=56 Total: 120' Assuming the walls will be 8' tall. The amount of studs needed for your shed on 16" O.C. is 120x12/16=90 studs of 96" precuts. Add a couple studs on each corner. Your total would be about 100 precuts for the walls. You also need to account for the bottom sill and the double top sill wich would be 120'x2 for the top= 240' and 120' for the bottom. That's 360'. You can use 16' lumber for those so 360/16=about 23 16' studs. That should take care of the walls. The roof is another story...