Measure of the health of a player's chip stack in poker
In no-limit or pot-limit poker,
a player's M-ratio (also called "M number", "M factor"[1] or just "M") is a measure of
the health of a player's 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 high 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.
The
term was named after Paul Magriel.
Calculation [ edit ]
The M-ratio is calculated by
the formula:
M = stack small blind + big blind + total antes {\displaystyle M={\frac
{\mbox{stack}}{{\mbox{small blind}}+{\mbox{big blind}}+{\mbox{total antes}}}}}
For
example, a player in an eight-player game with blinds ofR$50/$100, an ante ofR$10, and
a stack ofR$2,300 has an M-ratio of 10:
M = 2300 50 + 100 + ( 10 × 8 ) = 2300 230 = 10
{\displaystyle M={\frac {2300}{50+100+(10\times 8)}}={\frac {2300}{230}}=10}
That is,
if the player only makes the compulsory bets, he will be "blinded out" of the game in
10 rounds, or 80 hands.
Dan Harrington studied the concept in great detail in
Harrington on Holdem: Volume II The Endgame, [2] defining several "zones" in which the
M-ratio may fall:[3]
Zone name M-ratio "Optimal" strategy Green zone M ≥ 20 Most
desirable situation, freedom to play conservatively or aggressively as you choose[4]
Yellow zone 10 ≤ M < 20 Must take more risks,[3] hands containing small pairs and small
suited connectors lose value Orange zone 6 ≤ M < 10 Main focus is to be first-in
whatever you decide to play, important to preserve chips Red zone 1 ≤ M < 6 Your only
move is to move all-in or fold Dead zone M < 1 You are completely dependent on luck to
survive. The only move is to push all-in into an empty pot
Effective M [ edit
]
Harrington further develops the concept to account for shortening tables, as is seen
at the closing stages of multi-table tournaments. The M-ratio is simply multiplied by
the percentage of players remaining at the table, assuming a ten-player table to be
"full". [5]
M Effective = M × ( Players 10 ) {\displaystyle
M_{\mbox{Effective}}=M\times \left({\frac {\mbox{Players}}{10}}\right)}
Therefore, for
a player with a "simple M ratio" of 9 at a five player table, the effective M is 4.5:
M
Effective = 9 × ( 5 10 ) = 4.5 {\displaystyle M_{\mbox{Effective}}=9\times \left({\frac
{5}{10}}\right)=4.5}
This means that although the player's simple M value places him in
the orange zone, his effective M dictates a shift in playing style appropriate for the
red zone. In essence, ten times the effective M denotes the expected number of hands a
player can let pass before running out of chips.
See also [ edit ]
