It's long been a popular request for Poker Copilot: Adding the M-ratio to the HUD. It's a statistic that is particularly useful when a tournament approaches the bubble.
Here's a screenshot showing it in action:
It's an odd example of M because this hand was in a cash game. But you get the point I hope.
From Wikipedia on the topic of M-ratio:
In no-limit or pot-limit poker, a player's M-ratio (also called "M number", "M factor" or just "M") is a measure of the health of his chip stack as a function of the cost to play each round. In simple terms, a player can sit passively in the game, making only compulsory bets, for M laps of the dealer button before running out of chips. A high M means the player can afford to wait a number of rounds before making a move. The concept applies primarily in tournament poker; in a cash game, a player can in principle manipulate his M at will, simply by purchasing more chips.
A player with a low M must act soon or be weakened by the inability to force other players to fold with aggressive raises.