As the name suggests Stack to Pot Ratio (SPR) is a measure of how big your stack is relative to the pot. We use it as a way to determine how committed to you should be to the pot.

Stack-to-pot ratio (SPR) is a metric first published by Matt Flynn, Sunny Mehta, and Ed Miller in Professional No-limit Hold 'em: Volume One. It is calculated by dividing the effective stack against a given opponent by the size of the flop pot. (SPR always refers to the size of the pot and stacks at the flop, i.e. Between preflop and flop betting.) TODO: example etc. The stack to pot ratio is: 6.2 6.2 = 40 / 6.5 Depending on what blog you read or what poker book you have, you will find that there is conflicting information on what a low, medium and high SPR is. Some books will say that a low SPR is 2.5, others will say 3-4, and then others will say 6.

The SPR formula is simply:

Effective Stack Size/Pot Size = Stack to Pot Ratio

When your SPR is low, you should be prepared to commit with medium strength hands, when it is high you should be committing with the top end of your range. Unless of course you have a reliable read which suggests otherwise.

Let’s use a couple of examples to illustrate this.

The pot is $100 and you have $150 left in your stack (it could be a 4-bet pot, for example). You have AJ

The flop is J98.

Your SPR is:

How To Stack In Instant Pot

$150/$100 = 1.5 SPR

In a spot like this you have to be prepared to stack off with top pair top kicker. You have committed too much money relative to your stack size not to. The low SPR of 1.5 makes it easier for you to get your money in the middle. You could easily get action from a worse Jack, a worse pair, a heart draw or AK/AQ here when pot size is so small relative to the effective stacks.

When SPR is high

But what if we have the same hand and flop, but this time we have a stack of $195 and the pot is $10?

The SPR this time is:

$195/$10 = 19.5 SPR

Now stacking off with top pair could be a disaster unless you have a huge read on your opponent. If, for example, you bet and get reraised all-in on this flop you realistically are only beating a drawing hand and even that would win a lot of the time. You likely are up against an overpair, two pair, a set, a straight or a dominating combo draw if you get that much action. The SPR of 19.5 is a warning sign that you need a very strong hand here to commit a lot of chips to the pot.

It’s very situational and depends on your opponents, but when the SPR is 0-3 you should be prepared to stack off with one pair type hands and when it is higher than 6 you should be proceeding with caution unless you have sets or better. Anything between is a judgement call.

Before you start over committing to every pot you find yourself in with a low SPR a few warnings. First of all this doesn’t mean you should be 4-betting preflop with junk to justify stacking off with third pair post flop because the SPR said you should. You can orchestrate unprofitable situations preflop even if the post flop spot is technically profitable.

Secondly, SPR naturally gets lower with each street in Hold’em, when you put money in on the flop your SPR will be lower on the turn. This doesn’t mean you should be stacking off with weaker hands on the turn than you would the flop, this is where the Funnel Principle comes in to play.

Related Resources

Intro to SPR

Tackleberry with the lowdown on Stack to Pot Ratio

MTT betting

LuckyLukePS with a guide to betting in poker tournaments

We'll look at a couple of examples and then define the concepts properly.

Omaha example of SPR considerations

Let's say you flop the nut straight in pot limit Omaha. It's a bare nut straight, that is, you have no draws to stronger hands like a flush or full house.

You have $500 left in your stack and there is $20 in the pot. Now one player bets the pot ($20), another raises pot by betting $80 and two players call. What do you do?

Stackable Plant Containers

Most PLO players feel that the bare nut straight doesn't play well in a huge pot. It's the best hand right now but many cards would give you big troubles on later streets. If the board flushes or pairs you're looking at losing a huge pot. The straight may not even be a favorite to win the hand.

If, on the contrary, you had only $80 left in the stack, then it would be an easy call since you have the best hand and you can't lose any further bets if an opponent improves to a flush etc.

Holdem example of SPR considerations

Or say that you flop bottom two pair in holdem. If there's $20 in the pot and one opponent bets pot, your decision would probably depend on the size of your stack.

With $60 in the stack you might raise all in hoping that you have the best hand.With so short stacks, the opponent would bet with many hands that you beat, and if you lose it's not that expensive.

With $600 in the stack, you'd probably want to just call and see what develops on the turn. You'd want to keep the pot smaller and not committ too much with a marginal hand.

There are plenty of situations where your decisions at the poker table depend on the size of your stack compared to the size of the pot - the stack to pot ratio, or SPR.

Effective stack is what counts

As a matter of fact, it's not really your stack that counts, but the effective stack. That is, how much money you can lose in the hand.

if you're heads up, the effective stack is whatever stack is shorter. If you have $100 and your single opponent $50, the effective stack size is $50. That's how much you can lose in the pot.

If more than two players remain in the hand, there are several possibilities. As long as one remaining opponent has more chips than you, your own stack is the effective stack (for you).

If you have the biggest stack, the effective stack is the biggest one of your opponents' stacks. That's how much you can lose in the hand.

Definition of SPR

Now that we know what 'effective stack' means, the stack-to-pot ratio is defined as follows:

SPR = Effective stack / Pot

If all players have $500 stacks and there's $20 in the pot, your SPR is 25. This is a very high SPR. You could be looking at a huge pot and you need to plan your game accordingly.

With $20 in the pot and an effective stack of $80, the SPR is 4. This is a short-stack scenario and calls for very different strategies. Paople will bet and call with more marginal hands. (Basically since the fold equity increases compared to the implied or effective odds.)

We won't go into any specific strategies here. A lot have been written about those in various poker books, for example 'Advanced Pot-Limit Omaha' by Jeff Hwang or 'No Limit Hold 'em: Theory and Practice' by Sklansky and Miller.

Read them!

/Charlie River