Stack-to-Pot Ratio (SPR) is a simple but important calculation that every successful poker player must understand. It aids decision making in certain spots, most commonly when deciding whether or not to push all in.
In this guide, we’ll explain exactly what Stack-to-Pot Ratio is and offer practical advice on how to apply it to your own game.
What Is Stack-to-Pot Ratio?
First of all, let’s look at what Stack-to-Pot Ratio actually means. Ed Miller is the man who first coined the term, in his book Professional No-Limit Hold'em: Volume I. He explains that SPR is the effective stack size divided by the total pot size on the flop.
It’s important to use effective stack sizes rather than actual stack values since it’s not possible to win more chips than you have in front of you. For instance, if you have $50 and your opponent has shoved for $75, their effective stack is just $50. The extra $25 will be returned if you call, with just $50 remaining in the pot.
SPR Example
Picture a cash game where both you and an opponent have $500 in front of you. The villain raises to $6 and you, seated in the big blind ($2), are the only caller going to the flop. There is exactly $7 in the pot. You hold A 5 and the flop is A K T.
What are you going to do here as the first to act? Would you shove your $494 into the $7 pot? Of course not, right? That would be ludicrous. You have top pair, but serious kicker trouble. Plus there are obvious flush and straight threats on the board. With such big stacks, there is a lot of room for post flop play and such a manoeuvre would be all risk with no reward.
Everyone knows intuitively that an all in would be ridiculous. But why is it so crazy? After all, if you only had $5 left, you’d almost certainly shove in that same spot. With such a short stack, you don’t have time to wait for a better hand.
Again, we understand why at an instinctive level. But by looking at the exact Stack-to-Pot Ratio, it’s possible to quantify exactly whether or not a shove is justifiable.
Why Is Stack-to-Pot Ratio Important?
Stack-to-Pot Ratio allows us to put a specific value on a situation. We can use this to determine the exact strength of a post-flop hand and, as a result, figure out the correct decision.
As a general rule, high Stack-to-Pot Ratio scenarios mean that it’s trickier to play a hand on the turn and river. More skilful players will dominate these situations, as there is more room for nuanced play.
On the other hand, a smaller SPR scenario removes a lot of decisions from the equation. As such, players can simply shove with a hand like top pair and hope to realise their equity.
Applying SPR in Practice
Okay, so now that we understand the theory behind Stack-to-Pot Ratio, how do we put this into practice?
First of all, take the time to calculate the SPR every time you play a hand. Don’t forget that this value is flexible, changing as you progress through the flop, turn and river. Get into the habit of thinking about SPR as often as you would pot odds or any other concept.
Once you’re comfortable calculating the Stack-to-Pot Ratio, you can begin using it to inform your decisions. Here are some examples of common SPR scenarios and suitable hands that you can incorporate into your game.
Low SPR Situations
A small SPR situation would be one with a figure of 5 or lower. The most likely spot will be taking a flop after a 4-bet pot in a standard cash game. But it’s also possible after a 3-bet pot fairly deep into a tournament, or single-raised pots where a relatively short-stacked big blind defends.
We don’t want to get tricky in low SPR spots. You’re not looking to float a flop before check-raising the turn, for instance. The smaller the Stack-to-Pot Ratio, the greater the size of the pot relative to whatever chips are left to bet. As such, players are incentivised to play weaker holdings as they’ll be getting good odds to continue.
Since it will only take a couple of pot-sized bets to find yourself all in, we should be willing to shove a wider range. One pair will usually be enough, especially a top pair or an overpair to the board. Bottom two is also a prime candidate.
Shoving on the flop is justified as it brings fold equity into play and allows us to get value from mid-strength hands. It puts the opponent in a frustrating and difficult position. Even if we get called, we should still have a decent amount of equity.
Medium SPR
When the Stack-to-Pot Ratio is around 5 to 12, we obviously need a better hand than in small SPR situations. But it doesn’t have to be quite as strong as in a high SPR spot. We can add all flushes and straights to the range in medium SPR positions, as well as two pair.
Big draws are still useful, but they can be tricky to play. Since the SPR is lower, you may find yourself pot committed if you’ve got the right odds to continue. And if you miss the draw, you’ll end up stacked.
Medium Stack-to-Pot Ratio situations are a good time to play suited connectors and set mine with smaller pocket pairs. These speculative hands are not much use to you in small SPR spots. But they start to become profitable when you have the potential to win more chips from opponents.
High SPR
A deep SPR situation would be something around 12 and above. Now, opponents are much more reluctant to get into a big pot without a good hand. There is too much in their stack to risk shoving weaker hands like one pair.
When the Stack-to-Pot Ratio is high, there's a good chance that we are behind when re-raised. So we need to make sure we have stronger holding if we’re going to continue.
Good hands for these scenarios include sets, straights where you have the good end and bigger flushes. Powerful drawing hands can also make decent candidates to play in deep SPR spots.
Manipulating Stack-to-Pot Ratio
To make future plays as straightforward and successful as possible, think about the ideal post-flop SPR for your starting hand. Now you can tailor your bet sizes and raise sizing pre-flop, to engineer the perfect SPR on the flop. Or alternatively, use this to encourage you to stay out of the pot altogether.
For instance, let’s say you have pocket threes preflop when effective stacks are small. You already know that it’s not a profitable play to call a raise or make one yourself, as you’re in a low SPR situation. With little in the way of implied odds, it’s probably just better to stay out of it and await a better spot.
An example of manipulating the SPR might look something like this. Imagine holding A K with $50 effective starting stacks in a $0.50 / $1 game. You raise 3x BB and find one caller, reducing stacks to $47 and creating a pot of $6.50. The Stack-to-Pot Ratio is now 7.23, a medium SPR scenario.
This would be too great of an SPR to justify shoving if you were to make top pair. But that is about as good of a hand as you can hope to hit with your starting hand. So why not raise bigger pre-flop?
A raise of 5x BB would result in effective stacks of $45 and a pot of $10.50 if called. This new SPR of 4.29 means you are much more justified getting all in post-flop with one pair. And of course, you’re more likely to simply take the pot down pre-flop anyway.
Stack-to-Pot Ratio: Final Thoughts
That wraps up our guide to the concept of Stack-to-Pot Ratio in poker. Now that you understand exactly what the term means and how it can aid your game, it’s time to practise using SPR effectively.
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