Hi biff227

I think what you need to consider here is not the weight of the shed but the dimension. There are readily available calculators online, here's one: http://www.concretenetwork.com/concr...calculator.htm ( I just googled that) anyway. There you can punch in the numbers i.e width, length, and thickness of the concrete, and it will tell you how much bag of premixed concrete you need. something like that. I hope this helps.