Stack-to-Pot Ratios

What is a Stack-to-Pot ratio?

What is the relevance of SPRs?
Categories of Hands.
Specific SPR estimates.
Formulating strategy with SPRs.

What is a Stack-to-Pot ratio?

A stack to pot ratio describes the size of the effective stacks relative to the size of the pot. If the size of the pot is 10bb, and there are 40bb remaining stacks, there is an SPR of 4. (4:1) The simplest way to calculate the SPR is -

SPR = Effective Stacks / Pot-size

What is the relevance of SPRs?

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Effective stacks are 40bb. Hero is UTG with kk and open raises to 5bb. Everyone folds apart from the BB who flat-calls.

The flop comes j72. (Pot is 10.5bb. Remaining stacks are 35bb. SPR of ~3.33)

The BB checks. Hero bets 8bb into the 10.5bb pot. Villain shoves for 35bb. Hero calls.
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It’s true that villain can have hero beaten in this spot with a hand like JJ,77,AA. Given the stack sizes (and SPR) it’s completely conceivable that villain has a worse hand he is value-shoving like any Jx, QQ, TT. Perhaps sometimes villain even shows up with a semi-bluff like 98, T8, or even a pure bluff. Maybe he shoves a hand like 55 or 66 for protection/bluff even though he doesn’t like the board.

Given that villain can have a worse hand a decent amount of the time, this is an easy call for hero.

Same scenario, bigger stacks:

Now let’s take the same scenario – but this time with effective stacks of 300bb.

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Effective stacks are 300bb. Hero is UTG with kk and open raises to 5bb. Everyone folds apart from the BB who flat-calls.

The flop comes j72. (Pot is 10.5bb. Remaining stacks are 295bb. SPR of ~28.1)

The BB checks. Hero bets 8bb into the 10.5bb pot. Villain shoves for 295bb. Hero folds.
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The hands are the same, the opponents are the same playing from the same positions, but this time hero finds himself in a spot where it is very difficult to call. So what changed? The stack-to-pot ratio.

While it’s completely conceivable villain can be shoving worse hands for value and also bluffing when the SPR is ~3.3, it’s very unlikely he is going to be shoving anything less than a set for 300bb with an SPR of ~28.1.

Categories of Hands

In order to effectively use SPRs you must be capable of efficiently categorising hands into one of two main categories. There is a decent amount of crossover between the two, but they are defined as the following -

1) High value hands that suffer from reverse implied odds.
2) Speculative hands that benefit from implied odds.

The first category includes strong hands that typically make big pairs. Hands like AKo/AQo, AA, KK, QQ, KQo. As we’ve seen in the AA example these hands are usually very easy to play with low SPRs, but once the stack sizes get deeper they potentially run into difficulty. With high SPRs you need to be worried that your 1 pair hand isn’t good against the range villain wants to commit a larger amount of chips with.

The second category includes speculative hands. Hands like 78s, 64s, A3s, 22, 55. One of the most likely hands a suited-connector is going to flop is a draw. With a low SPR a draw is not going to have sufficient implied-odds to continue on the flop or turn. The higher the SPR the better hero’s implied odds and the more profitable his drawing hand will be (assuming he is not drawing to a dominated hand).

Small pockets like 22/55 are slightly different in that they won’t flop a draw much, but instead will flop a very strong hand (set) a small percentage of the time. In terms of set-mining strategy hero is going to need to make a sufficient amount postflop to compensate for all the times he misses. With a low SPR this will not be possible. To an extent, the higher the SPR the more profitable the set-mining opportunity (until the SPR becomes so high that villain is only stacking off with oversets).

What about a hand like QTs however? Is it a speculative hand or a big pair hand? It’s one of the hands that sits in both categories. How you choose to play it will depend on the kind of SPR you can create for postflop play. If you can only create a very low SPR due to the stack sizes you will generally play it as a big-pair hand, while if creating a high SPR is an option you can profitably play it as a speculative hand.

Specific SPR Estimates

The first thing to understand is that preferred SPRs are estimates, not mathematical fact. Against a loose player you will be able to profitably commit postflop with higher SPRs, while against a tight player you may prefer to only commit with a lower SPR. Here are some rough estimates -

Top Pair Good Kicker hands – AK/AQ/AJ/KQ/KJ etc It’s estimated these play best with an SPR of around 4. They will also play ok with an SPR of 20+ assuming you take a pot-control line or flop better than 1 pair.  However, these hands play badly with an SPR of 13. An SPR of 13 will allow for exactly 3 potsize bets on the flop/turn/river. Often you may only want to bet 2 streets for value with TPGK hands, depending on your exact hand and the board texture. If this is the case you leave your opponent with a nasty river bullet, especially if he is in position and you check the river to him. You put yourself in an ugly spot where folding is possibly too tight, while calling is too loose. With a lower SPR that river bullet won’t exist, and with a higher SPR your opponent has to fear you coming back over the top. He may also play less aggressively on earlier streets due to the deep stacks which could make it easier for you to take a pot control line with your TPGK hand.

Overpair hands – AA/KK/QQ etc. These play similarly to TPGK hands but will flop stronger in general. As a result they play better with a slightly higher SPR of around 6. Again, they suffer somewhat with an SPR of around 13 but play ok with an SPR of 20+ assuming you take a pot control line.

Speculative connectors – 56s/97s/A2s/K4s. As discussed these hands need a high enough SPR that they have sufficient implied odds to continue with any flopped draws. They also need to make enough money when they do hit to make up for all the times they miss. Ideally you want an SPR of 13 or more, but to an extent the higher the better.

Small pockets – 22/55/77. As discussed these hands need to make enough postflop in order for the setmining opportunity to show a profit in the long run. Ideally you want an SPR of 13 or more, but to an extent the higher the better.

Formulating Strategy with SPRs

Your general strategy should be the following:

Play as many hands as possible with your preferred SPR, while denying your opponent the opportunity to play at a beneficial SPR for him.

Think of an ancient battlefield. The armies involved played a crucial part, but the terrain chosen might mean that one side had a big advantage regardless of numbers. The cards you bring to the fight are important, but you can create an advantage for youself by choosing the terrain (SPR) for your battle.

It may not always be possible to make preflop play which creates a favourable SPR for you. Simply understanding SPRs is going to confer an advantage however. There are still a huge number of players out there that don’t understand that their preflop/postflop play are linked. They make their “standard” plays preflop and then proceed to continue postflop like it’s an entirely separate game.

A player with a good understanding of SPRs may be able to pre-empt how a hand might play and begin to formulate possible lines even before a flop is ever seen. Such a player is also able to decide whether their hand is a TPGK hand or a speculative hand given the SPR’s involved. Remember, some hands can fall into either category, but how you choose to play them will depend on the SPR.

On other occasions you may find yourself in a situation where you have multiple options, perhaps options that appear to have a similar expected value at first glance. Upon analysis you see that one option sets up a favourable SPR, while the other doesn’t. Choosing the option with the favourable SPR will create an edge in the long run, assuming you understand why one SPR is favourable over another.

Achieving your target SPRs is something that takes a lot of practice and experience.