Stack to Pot Ratio

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Published: 17/12/2010

One of the hottest new topics among Texas Hold’Em Poker players is a concept called “Stack to Pot Ratio” or SPR. It was pioneered by author Ed Miller in his 2007 book entitled “Professional No Limit Hold’em: Volume 1.” Miller proposed an equation that helps a player know exactly what risks to take or avoid after the flop, namely:

SPR = ESS / FPS

In this equation, EPS = Effective Stack Sizes and FPS = Flop Pot Size. By “effective” stack size, Miller means the smallest stack of chips held by any player remaining in the hand post-flop, as that is the most that said player can risk. According to Miller, the resulting calculation is equivalent to the ratio of Risk to Reward, so that a high SPR presents a more risky situation than a low one. Note, too, that SPR can only be used to assess situations post-flop, not following the turn or the river.

SPR in Action

As a simple example, consider two players, Carla and Carlos, going head-to-head post flop. The pot stands at £20. Carla has a stack of £80, while Carlos has £640. Using the formula for Stack to Pot Ratio yields an SPR of 80/20 = 4.

On the other hand, if Carla had had a stack of £800 instead of £80, then the effective stack size would have been Carlos’s for an SPR of 640/20 = 32. The larger the smallest stack is relative to the pot, the greater the risk will be, and in this example, it is 8X greater.

According to Miller’s figures, when the SPR is lower than 6, the risk of proceeding with a hand post-flop is low. Good hands to play under such conditions are overpairs, top pairs, and bottom two pairs, especially when the pots are small. Miller would advise players to always try to play in hands with low SPR numbers.

For situations where the SPR is between 7 and 16, the risk is said to be moderate. Within this range, the top two pair, sets, flushes, straights, and good drawing hands are all fine hands to play. Notice that the hand strength has increased as the risk has gone up.

When the SPR exceeds 17, risk is deemed to be high. Such a situation is best played with sets, strong drawing hands, big flushes, and high-end straights. Such hands are practically guaranteed to win pots, so the high risk is warranted.

Setting up the SPR

Armed with this information, a player can use some strategies to set up a desirable SPR. For example, when shortstacked and holding premium cards such as A-K suited, there may be little danger of raising pre-flop with the intention of going all in later if called. Building the pot and reducing one’s already small stack ensures a very low SPR.

By the same token, when all players’ stack sizes are low and the resulting SPR is likely to be low as well, there is little value in raising pre-flop on small pocket pairs or suited connectors. Limping in or folding is preferable.

Thinking about the likely SPR of a hand pre-flop can help a player decide how much to raise, too. A raise of 6X the Big Blind will be more effective in lowering SPR than one of 3X or 4X. Not entering a pot at all can sometimes make the SPR more risky for players that do.

Again, this type of strategizing is still quite new. Anyone wishing to apply it is well advised to read Miller’s own writings on the subject and then to observe how it might be used in play before actually giving it a try.

Published on: 17/12/2010

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