Poker Tips & Strategies: Harrington's M Zone System

Gerald Hanks

Friday, July 12, 2013 6:26 PM GMT

“Harrington on Hold'em”, World Series of Poker Main Event Champion and poker analyst Dan Harrington detailed a brilliant and concise mathematical system for success at poker tournaments.

Harrington's M-Zone System 

One of the concepts he developed was the “M-ratio”. Harrington revises the concept of basing the strength of relative stack sizes on the number of big blinds in each stack. Instead, Harrington bases his M-ratio on the number of orbits of the button that occur until the player's stack is obliterated. 

How to Calculate M Ratio

Five major factors go into calculating a players M-ratio:

  • Stack size (S)
  • Big blind amount (BB)
  • Small blind amount (SB)
  • Ante amount (A)
  • Number of opponents (P) 

The total cost of one orbit of the button (O) is the sum of the blinds and antes:

O = SB + BB + (A * P)

At a full table, the M-ratio is the ratio between the stack size and the cost of one orbit of the button: 

M = S / O 

At a short table, the M-ratio is prorated to take in the shorter button orbits:

M = (S / O) * (P / 10)

Example 1: A player has 8,500 chips. Blinds are 200/400 with a 25-chip ante and 10 players at the table.

O = 200 + 400 + (25 * 10) = 850

M = 8500/850 = 10

Example 2: A player has 28,000 chips. Blinds are 1200/2400 with a 200-chip ante and 6 players at the table.

O = 1200 + 2400 + (200 * 6) = 4800

M = (28000/4800)  * (6/10) = 3.5

Harrington also developed the concept of “M-zones” to help players make decisions based on their M-ratios.

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Green Zone: M is 20 or Higher

Players often approach the early periods of a tournament, where the stacks are deep and the blinds are low, much like a cash game. The “green zone” allows the player to play the same style as he would in a cash game. However, these players should also be aware of the structure and timing of the blinds so that they don't fall into the more dangerous M-zones through either early recklessness or hesitancy to engage in risky situations.

Yellow Zone: M Between 10 and 20

Players in the “yellow zone” must be more selective with their starting hands and more aggressive with the ones that they choose. Sklansky's “gap concept” is the guiding force for players in this zone. Players in this zone must fold marginal starting hands, such as small pocket pairs, middle suited connectors or unsuited big cards, and wait for hands where they can use pre-flop aggression and take down the blinds and antes to survive another round.

Orange Zone: M Between 6 and 10

The “orange zone” requires a similar approach to the “yellow zone”, as starting hand selection and pre-flop aggression are the keys to survival. The major difference is that “orange zone” stacks are often just big enough for the first player to act to make an all-in pre-flop bet and scare off opponents, but just small enough to get heads-up against a marginal hand to call and try to double up.

Red Zone: M Between 1 and 5

The blinds and antes, especially at a short table, are coming around too fast to wait for a quality hand. The only move available to a “red zone” player is to push all-in pre-flop, especially if he is first to act.

Dead Zone: M Less Than 1

With only a few hands left before the “dead zone” player gets blinded out, the only choice is to “push and pray”. “Dead zone” players can expect plenty of callers to get them out of the way, but one lucky turn of the card could bring the patient back to life.

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