Beef Bone Broth: How much should I end up with per starting bones?
You can choose. Just taste it. Too strong, more water, too weak, boil down. It is better to leave the lid on while boiling. That will make the broth cloudy, but more tasty.You can always filter it and clear it up with egg white.

For easy storage: boil it down, really down,and freeze. i dont think more than a litre of a kilo of bones will be very strong