I was looking to purchase a heavy bag that I can hang up at home just to keep fit as I don't get much time to go to the gym anymore. So I was wondering what kind of bag to buy, size and weight etc.

My main concern is the weight of the bag. How heavy should my bag be? I weigh 80kg myself and have a few years of boxing experience so I have a decent punch. I don't want a bag that is too light and I'm not sure how heavy the bags usually are.
If you guys have any tips, advice or recommendations please share.