Effective Stacks and the Rule of 5/10

Effective Stacks and the Rule of 5/10

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Have you already heard about the term “effective stack” understood its strategical implications on your poker game? If not, then you should read this strategy articles. The concept of effective stacks is important in all No Limit Texas Hold’em variants, both in cash games as well – and even more – at Sit and Go’s and other poker tournaments.

Definition of Effective Stack

The effective stack is the smaller amount of chips either you or your opponent has. If you have 1000 chips left in a tournament and the only opponent in the hand has 700 chips, then you cannot win more than all of your opponent’s 700 chips. Thus, the effective stack size is 700 chips. Even if you both go all-in, you can play only for those 700 chips. The additional 300 chips you have are not relevant.

Odds and Effective Stacks

The effective stack size measures the maximum profit that you can achieve in one hand. This is important if you want to calculate the probability of winning a hand (odds). If the effective stack in relation to the bets is high, then you can play with marginal hands, hoping to stack your opponent and win all his chips. Even if the probability of winning with a suited connector or a low pocket pair is low: the potential win of the whole stack of your opponent allows you to call a preflop bet with a marginal hand.

The situation is different if you or your opponent has only few chips left in relation to the bet. Marginal hands become unprofitable in such a situation. Let’s have a look at a practical example of effective stacks with the “Set Mining” strategy.

Set Mining and Effective Stacks

With set mining, you try to flop a set with a low pocket pair. After the flop, you are pursuing the “no set, no bet” strategy. This means that if you do not make your set, you won’t put any more chips in the pot and play check / fold.

Up to which effective stack size set mining is a profitable strategy can be either calculated or estimated using a rule of thumb.

You can calculate the probability of not flopping a set by multiplying 48/50 x 47/49 x 46/48. The probability of not flopping a set is therefore 88.25%. So you will flop a set or even quads in 11.25% of the cases. But even with a set on the flop you won’t win always – the opponent can achieve a better set, for example, or a straight or a flush. Using examples with various flops we estimate that a set will win the hand in about 7 of 8 cases. The probability of making a set with a low pocket pair on the flop and winning against one opponent is therefore just over 10%.

The Rule of 5 and 10

This calculation can also be found in the famous “Rule of 5 and 10” (first stated by Robert Ciaffone). The rule applies to the game before the flop and says that you may call a preflop bet in a tournament with speculative hands only if you do not have to pay more than 10% of the effective stack size to see the flop. If seeing the flop costs you less than 5% of the effective stack size, then you can call the bet in any case. If the call would cost you between 5 and 10% of the effective stack size, then you have to weigh the decision carefully – there are reasons to call and reasons to fold the hand. Read our tips on this though call decision at the end of this article.

Speculative Hands and Effective Stacks

In principle there are three groups of hands with which you can apply the “rule of 5 and 10” in connection with effective stacks. The first and most promising group are small pocket pairs like 5-5. The second group are suited aces like Ace-Four and the third group are of suited connectors like 8-7.

Examples of Effective Stacks and the 5 / 10 Rule

Let’s briefly look at two practical examples of the effective stacks and the 5 / 10 rule.

Example 1: You have a pair of fours, 1000 chips and are sitting in the big blind (blinds 25/50). All players have folded except the player on the button (with 700 chips) who makes a 3 BB raise. The effective stack is thus 700 chips (the blinds are not counted in this simplified rule). Because you have to pay 100 chips to play for 700 chips (14%), you should fold this hand.

Example 2: You’re sitting with 2000 chips on the button and hold 7-6 suited. One player (Stack 2500 chips) made a mini-raise to 80 (blinds 20/40). The two players in the blinds are passive and both have 3000 chips. You assume that these players will call or fold to the mini-raise. The effective stack size is 2000 chips. Because 80/2000 is 4%, you should call the mini-raise.

Decision Tips for the 5 / 10 Rule

You will often be in a situation where the bet in relation to the effective stack is between 5% and 10%. The following points favor making a call in such a situation. You should call more likely:

  • The closer you are at 5%
  • The more dead money is in the pot
  • The higher the probability is that your opponents are ready to go all-in with medium strength hands
  • When your call closes the action before the flop (no possibility for a reraise)
  • If you have position on the opponent (late position instead of sitting in one of the blinds)
  • The more players are in the hand (this makes it more likely to win the stack of at least one of your opponents)
  • The less often your opponent makes continuation bets (which gives you the opportunity to get a “free card” on the turn)