This article was written by blackrain79.com contributor Ryan Lewis.
There are all sorts of mathematical equations that can be utilised in poker to assist players to help with their decision making in game.

Stack to Pot Ratio, or SPR for short, is a tool for helping to plan your hand around commitment decisions. In short, by providing a quick, easy framework for relating the size of the pot to the remaining effective stacks, you’ll be able to more easily determine if your hand strength warrants playing an all in pot or not. The stack-to-pot ratio (or SPR for short) principle was coined by Ed Miller in the book Professional No-Limit Hold'em: Volume I. In this article I aim to explain the basics of SPR in poker and show you how it can be used to make your post-flop decisions a lot easier in cash games. This article is merely a brief introduction and overview of SPR. Note – SPR stands for Stack to Pot Ratio. I think a lot of SPR importance is based solely on the texture of the games you are playing in. To say a general statement like 'SPR of 13 is bad for top pair' would be wrong, since with aggressive history 13 is an amazing, optimal even, spr for top pair.

In order to become successful long term players, we must have a good understanding of poker math theory so it can be applied in real time during live or online play.
Although not the most sexiest subject in the game, a lack of understanding in basic math can lead to costly errors down the track and force our win rate or return on investment to take a substantial hit.
In this article I will introduce the stack to pot ratio equation and how you can use it in game to boost your win rate and results.

What is the stack to pot ratio?

The stack to pot ratio (SPR) is a simple basic calculation that tells us how much we are willing to risk to win a hand.
The equation is calculated post flop and applies on the flop only and before any betting is done. The formula is:
For example, we head to the flop as the pre flop raiser and only the big blind calls. The pot size is 6.5BB. I have 97BB in my stack, the big blind has 40BB in theirs.
The effective stack is 40BB, as I can only win what the big blind has remaining. 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.
As per usual in life the answer lies somewhere in the middle.
Through experience of playing hundreds of thousands of hands I have come up with my own conclusions on optimal stack to pot ratio numbers:

• Low SPR: < 4
• Middle SPR: 4-10
• High SPR: > 10

How to interpret the stack to pot ratio

By calculating the SPR we can make a logical decision if we want to play for all the money on the flop.
Below is a hand strength guide which we can use to determine how willing we are to play for all the money on the flop based on the stack to pot ratio:
The basic premise is the higher our SPR is, the higher our hand strength must be to auto stack off on the flop. Overpairs also do well in SPR’s of 6 and below.
Bare also in mind that these numbers are fluid. If you have a specific read on villain and know they like to stack off light, then getting it in with top pair when the SPR is 6 is viable.
Another point to keep in mind is 3bet pots usually create an SPR of roughly 4. This allows you to stack off comfortably with top pair and overpair type holdings.
Draws can be tricky to play with middling SPRs because you can be forced to call it off on the flop if you are presented with the right pot odds.
This can happen if you check raise the flop from the big blind with the nut flush draw and then face a jam. If presented with correct pot odds I advise to make the call, even if the SPR suggests otherwise.

Examples of using the stack to pot ratio

Alright, let's look at a few different examples of using stack to pot ratio in poker. Hopefully this will give you a better understanding of how to use SPR at the tables yourself.

Low SPR example

Button (Hero) 100BB vs BB (villain) 26BB
We hold A♠ K♣
Flop
4♠ 8♦ A♥
Pot is 6.5BB, SPR is 4. Villain donks for 3BB.
Hero should raise to 9BB and look to call a jam from the BB.
This is an easy stack off opportunity on the flop. We flop top pair top kicker in a low SPR of 4.

Middle SPR example

Button (Hero) 100BB vs BB (villain) 50BB
We hold 4♥ 4♣
Flop
4♠ 6♦ 7♦
Pot is 6.5BB, SPR is 7.7. Hero cbets 4BB. Villain check raises to 12BB.
Hero should jam.
Here the SPR is a little higher at 7.7. We flop bottom set and face a check raise on a wet board.
On this flop we should look to get it in immediately as there are many cards on the turn and river that will kill the action.
Any diamond, 3, 5, 8, 9 and T (almost half the deck!) are bad cards for us and we would rather get our money in on the flop when we are ahead the majority of the time.

High SPR example

Button (Hero) 100BB vs BB (villain) 100BB
We hold A♠ A♥
Flop
8♠ 8♥ 5♥
Pot is 6.5BB, SPR is 15.4. Hero cbets 2.5BB. Villain check raises to 10BB.
Hero should call.
In this example the SPR is high at 15.3. Our threshold for stacking off on the flop at this level should not be overpairs. Hero should call and reassess the action on the turn.

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How the stack to pot ratio can help your poker win rate

Here are a few concepts we can use both pre flop and post flop to assist us in how we plan a hand. First we need to take note of our opponents' stack sizes.
One of the most important and underrated skills we can undertake is to be more aware of our opponents stack size when heading to the flop.
Once we have a rough idea of the SPR, we can plan accordingly and decide whether we want to play for all the money before we perform our action.
You should have a rough idea of the SPR in every hand you play.
We can also exploitatively fold and not cold call marginal holdings such as low pocket pairs and suited connectors pre flop when facing an open raise from a short stacked player (60BB or less).
These holdings perform best with SPRs of 10 and higher.
The logic here is that you need to have the opportunity to win a large pot to balance out all the times when you call a raise and are forced to fold when you miss.
This is something that Phil Ivey talks about in a lot more detail in his recent MasterClass poker training.

Tailor your preflop bet sizing to your preferred stack to pot ratio

This situation will occur usually when we face opponents who open limp with a short stack. The general advice is to isolate the limper by raising to 4BB if you have a hand worth playing.
I would add to this advice that you can and should exploitatively raise larger to at least 6BB (or sometimes higher) when you hold a high pocket pair.
The limper will still call the majority of the time and by raising larger you create a larger pot heading to the flop which creates a smaller stack to pot ratio.
Smaller SPRs benefit big overpairs as you can easily get it in on the flop if facing aggression. By the way, I have already written the complete guide on when to fold your overpair.
We can also use this advice when 3 betting. Instead of 3 betting to a conventional 9 or 10BB we can opt for a larger sizing, such as 11 or 12BB.
If our 3bet is called we often head to the flop with an SPR of under 4 (assuming we are playing for 100BB), which can make our decisions easier if we decide to play for all the money.
I would advise against opening the pot (meaning we raise first in before any limpers) pre flop to a sizing higher than 3BB.
Even though this creates a smaller SPR, it forces your opponents to play perfectly against you by calling tighter and 3betting hands that have you crushed.
Unless there are major whales at your table, your raise first in size should be between 2.5-3BB. Remember we make money in poker from our opponents mistakes, not by forcing them to play well.

Proceed with caution when playing deep stacked

There is no worse feeling in poker than accumulating a 200BB stack, only to lose it all after overvaluing an overpair or the low end straight. Or having to think about folding bottom set on the flop when the SPR is 30.
Personally I hate playing deep stacked and to this day I avoid it like the plague. I make a conscious effort to reload the table once my stack is 150BB or higher.
I prefer to keep my decisions as simple as possible at the table and I achieve this by sticking to a stack size of around 100-150BB.
I'm not saying that you should do this as well but mastering how to play one stack size is superior than being average at short, regular or deep stacked.
If you stick to one stack size then you get used to what the SPR’s will be and your post flop decisions will become much easier.
If you find yourself playing deep stacked for 200BB often then be aware that the SPR will be between 25 and 30 routinely.
That means your threshold for stacking off on the flop should in theory be much higher and will be narrowed down to middle and top set, and nutted flushes and straights.
For much more on playing optimal deep stacked poker (and how to use SPR when super deep), check out the The Upswing Poker Lab.

Final thoughts

The stack to pot ratio is a simple math calculation we can utilise on the flop to decide how willing we are to risk our stack to win the hand.
The higher the SPR is on the flop, the higher our threshold and hand strength will be for getting all the money in.
Try and make a habit to know what the SPR is every hand you play so you know how to proceed on the flop if you face aggression.
In doing so it will allow more clarity in our post flop decision making process.
Lastly, if you want to know the complete strategy that I have used to crush small stakes poker games as a 10+ year pro, make sure you grab a copy of my free poker cheat sheet.
This article was written by Ryan Lewis. Ryan specializes in 6max cash small stakes online poker. He focuses on playing a fundamentally strong tight and aggressive strategy. He particularly enjoys the statistics and game theory side of the game. You can follow him on Twitter right here.
Let me know your thoughts in the comments below on stack to pot ratio. Do you use stack to pot ratio at the poker tables to improve your decision making?

There's also a handy classroom section on SPR starting at 6:26 in SplitSuit's 'Playing AA' video.

The stack-to-pot ratio (or SPR for short) principle was coined by Ed Miller in the book Professional No-Limit Hold'em: Volume I.

In this article I aim to explain the basics of SPR in poker and show you how it can be used to make your post-flop decisions a lot easier in cash games.

This article is merely a brief introduction and overview of SPR. I highly recommend you buy the book to feel the full force of 70 pages worth of SPR euphoria.

1. SPR equation.
1. Benefits of SPR example.
1. High SPR situation.
2. Low SPR situation.
3. SPR example evaluation.
1. Good hands for low SPRs.
2. Good hands for medium SPRs.
3. Good hands for high SPRs.
1. Tailoring your preflop raises.
1. Example of raising to 3bb.
2. Example of raising to 6bb.
2. Not entering pots.

I) What is SPR?

SPR is the effective stack sizes divided by the size of the pot on the flop.

Let's say you raise to $6 in MP before the flop in a $1/$2 NL cash game. One opponent calls on the button and both of the blinds fold. If both you and your opponent have $100 in your stack, the stack to pot ratio would be:

• $94 : $15
• SPR = 100 / 15 = 6.3

To put it another way, in this example the remaining effective stack sizes are 6.3 times the size of the pot. Easy stuff really.

SPR can also be considered the ratio of risk : reward. In every no limit hand, the pot is the reward and the size of the effective stacks is the potential risk. Therefore the greater the SPR, the greater the risk : reward ratio.

A) SPR equation.

The SPR equation. It's straightforward, but it could still do with some explaining.

• Important points about working out SPR.
• You must use effective stack sizes. If you have $150 and your opponent only has $100, then the effective stack sizes are $100, as you cannot win or lose more than $100 against this player.
• SPR is worked out on the flop only. Stack to pot ratios are not going to be used for the turn or river.

II) What is the use of SPR?

By taking control of SPR you can make post flop play a lot easier for yourself.

Low SPR situations are simple to play, as they greatly reduce the amount of post flop actions and decision that you are required to make because there is so little room for manoeuvre due to the large pot size and small effective stacks. You're not going to be floating the flop and check raising all-in on the turn if the flop is $10 and you have $20 left in your stack.

High SPR situations can be a lot trickier to play (depending on what sort of hand you have on the flop) because there is a lot of money left in the stacks to be played with on the flop, turn and river.

Different strengths of hands can be more suited to either high or low SPRs. Therefore, if you know what sort of SPRs your hand plays well in, you can manipulate the pot sizes by the way you bet or raise preflop, or avoid certain situations altogether (by folding) to land yourself in a good SPR situation for your particular hand.

A) Benefits of SPR example.

The best example of SPR is when you have a top pair hand like A K on a flop of K T 9. We have top pair, but the board is highly coordinated and in all honesty we'd really prefer to bet and just take this pot down on the flop.

i) High SPR situation.

If the pot size is $10 and the effective stacks are $200, the SPR is 20. If we bet this flop and get raised we are put in a very tricky situation, as we could well have the best hand here but we're not really prepared to commit too much money with just top pair.

If we do end up getting it all in on this flop or on the turn or river the chances are that we do not hold the best hand. This makes playing top pair hands like this tricky if the SPR is mid-sized or high.

ii) Low SPR situation.

If the pot size is $10 and the effective stacks are $30, the SPR is 3. If we bet this flop and get raised we are in a much more comfortable position to call or raise all-in, as we do not fear further bets on the turn or river.

Sure, our opponent could still hold a better hand but the risk here is much lower. We are committed to the hand and so putting all our chips in the middle is a much easier decision.

iii) SPR example evaluation.

In the two different scenarios above the strength of our hand did not change, yet the outcomes were very different due to the stack to pot ratio. With the low SPR of 3 the risk is much lower relative to the reward, which makes it very easy for us to call all-in with our top pair hand.

III) High, medium and low SPRs.

• Low SPR = 0 - 6
• Medium SPR = 7 - 16
• High SPR = 17+

These SPR figures are very rough guidelines and their implications will vary greatly depending on how loose or tight your opponents are. They also mean nothing unless we have an idea of which hands play best depending on the stack to pot ratio.

A) Good hands for low SPRs.

• Overpairs.
• Top pair.
• Bottom two pair.

These are the sorts of hands that we do not want to play big pots with, as the bigger the pots get the greater the chances are that we are behind. Low SPRs reduce the number of decisions we need to make with these hands, which makes them a lot easier to play and thus more profitable situations over the long run.

With mediocre hands like these, you want to to avoid becoming pot committed after starting with a full stack.

B) Good hands for medium SPRs.

• Top two pair.
• Sets.
• Good drawing hands.
• Flushes and straights.

These are much stronger hands than the ones above and will remain as the best hand when you're all-in often enough to keep them profitable when the SPR is between around 7 to 16.

The higher likely SPR also makes it profitable to play more speculative hands like small pocket pairs and suited connectors that infrequently hit big flops, as there is a lot more money to potentially be won from the hand on later betting rounds.

C) Good hands for high SPRs.

• Sets.
• Strong drawing hands.
• Big flushes and high-end straights.

These are the hands that are almost guaranteed to win you the pot. If the SPR is high, you want be be sure that you have near enough the nuts or a draw to pretty much the nuts if there is a lot of action. The last thing you want to do in high SPR situations is get a lot of money in to the pot without a very good chance of winning.

IV) How to get good SPRs.

Depending on the type of hand you hold before the flop, you should have a rough idea of the ideal SPR for making your post flop play as easy and as profitable as possible. There are two things that you can do to get yourself in ideal situations in terms of SPR:

1. Tailor your preflop raises to set yourself up for the ideal SPR.
2. Do not enter the pot in the first place.

A) Tailor your preflop raises.

You're not always going to have the luxury of tailoring your preflop raises to get that perfect SPR, but when you do have the opportunity you should take advantage of it.

i) Example of raising to 3bb.

You hold A K and you and an opponent have $100 effective stacks in a $1/$2 6max NLHE game. If you raise to 3bb from MP and your opponent in the CO calls, you will have an SPR of 6.3 ($94 : ) on the flop.

This SPR may well be a little too high for you to justify putting all of your chips in the middle if you hit top pair on the flop, especially so if your opponent is tight as there is a greater likelihood that they are only going to be willing to get all their chips in the middle they will have a better hand than TPTK.

ii) Example of raising to 6bb.

Using the same example as above where the effective stacks are still $100, let's say we raise to 6bb ($12) instead of 3bb preflop. If our opponent again calls we will have an SPR of 3.3 ($88 : ) on the flop.

With this lower SPR we will feel a lot more comfortable putting all of our chips in the middle if needs be. In addition the chances are that all of the money will be in by the turn, which saves us from a potentially difficult river decision.

B) Not entering the pot.

If you have a small pocket pair like 44 and the effective stack sizes are fairly low, it is not going to be profitable to raise or call raises as the SPR is going to be low also.

With low SPRs you are going to have very little in the way of implied odds (or fold equity if you turn your hand in to a bluff later on down the line), which means that you are far better off folding hands like small pocket pairs and suited connectors if you anticipate the SPR will be low.

V) Evaluation of stack to pot ratios in poker.

One of the key points that you should take from this article is that planning your hands from the start is vitally important for setting yourself up for profitable and easier-to-play situations later on in the hand. Another key point is just how much of an effect pot sizes on the flop can influence the way you play your cards.

You're not always going to be able to grab SPR by the horns and create flop pot sizes exactly how you want them, but nonetheless opportunities to tailor SPR will occur, so don't pass them up when they come around. Trust me when I say that post flop play gets so much easier when you plan your hands and use your knowledge of SPR effectively.

Again, this really is the tip of the iceberg when it comes to SPR. I'd highly recommend you pick up a copy of Professional No-Limit Hold'em: Volume I for more information on this topic. This is the book that also contains the invaluable REM process framework.

Alternatively, this 'concept of the week' article on SPR at 2+2 is also pretty awesome.

Go back to the awesome Texas Hold'em Strategy.

Poker Term Spring

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