How much should a boxing bag weigh for a beginner?

I'm looking on amazon for a boxing bag and there are a lot of different sizes.|||Compromise, Forget Amazon. Go to Proboxingequipment.com and order an 80 lb. bag. Get the 22 oz. vinyl/nylon bag. (Very inexpenwsive, but used in pro gyms),|||its not nessesarily based on beginer or master levels, its based on your weight or height, try a 40 pounder if you about like 10-12 and about 115 lbs, or a 60 pounder if your about 130, finally pass on to like a 80-100 if you hit kinda hard and dont want a light bag to be flying all over the place, try a heavy bag if you want the bag steady and your about 15 and up..|||get a 100 pounder. I used it when i was a beginner