You will know roughly what it weighs when you start picking it up. Also you check it over when you are covering it for transport. Get more money before you put it on the truck or drop right there. That's why you stick to the rules you put in places! Put what you don't take every were to be read. Receipts, sticker on every corner of the dumpster. Although in our areas its almost cheaper to get rid of it. Some dumps for concrete are free or $6-8 a ton.