I prefer Harrington's M number...it gives you the number of orbits you can play with the chips you have left.
the M number is the total of the BB, the SB and the the antes of the players at the table.Add that up and divide it into your stack and that is your M. So if, for example , the BB is 100, SB is 50, and 7 players payng a 10 ante, , the total is 220, so if you have say 2200 stack, you have a M of 10. That number dictates the changes in strategy you need to make as your M fluctuates with your play. It's all laid out nicely in his book Harrington on Holdem