SPR, short for stack-to-pot-ratio, is a powerful concept that can help you take better lines both preflop and postflop. If you can understand and apply SPR strategy in poker you will have a mathematical framework for commitment. Here is the SPR formula:
SPR = Effective Stack Size / Pot Size
We simply take the effective stack (the smallest of the stacks involved in a hand) and divide it by the pot size. So if we both have $200 and the pot is currently $10, we are in a 20 SPR pot.
Calculating the SPR is simple, but what does the number actually mean? Well SPR was created as a preflop/flop metric for commitment level. Or put another way, SPR is used to mathematically assess whether or not we are committed to a pot with certain hands in your range.
Let’s visualize this with a 200NL example:
MP OPENS TO $6 | CO CALLS $6
HERO (BTN) 3BETS TO $28 | MP CALLS |
At this point, the effective stack is $197 (villain’s stack is the smallest stack) and the pot is $65. So the SPR is $197/$65 = 3. This is a small SPR and is a more common SPR in squeeze pots, 4bet pots, and/or when playing against smaller stack sizes. In single raised pots it’s very common to see 13 SPR pots and normal 3bet pots tend to be 3.5-5 SPR.
What a small SPR actually tells us is that we are committed to the hand with any top pair (or better) hand. So in the earlier example, if we CB and he shoves, we are calling. If we checked and he shoved the turn, we would call. If we CB and he called, we would be committed on all turn cards.
If the SPR were larger, say 9, it would change things as we are no longer in an “automatic stack-off” SPR. The graphic below shows the SPR zones that I use, and notice that less than 3 is an auto-stack off with top pair or better, between 3-6 is situational and based upon villain/board texture, and more than 6 SPR isn’t a default stack-off (although there are obvious spots where we might against fish or with very strong hands).
We can glean a couple of useful things from this SPR concept. First, is that we want to be aware of the SPR we are creating. If a 40bb players open to 3bb and we were to call with 76s from the BB, we would be involved in a 5.7 SPR pot (37bb/6.5bb). Suited connectors and setmining hands perform best in very deep SPR pots where there is lots of playability and implied odds. With an SPR like 5.7 we won’t have the necessary flexibility to see our draw to full fruition, and that’s before we discuss the fact that we are OOP…
We can use the same concept when thinking about 3betting. Say a fish with 50bb opens to 3bb and we are thinking about 3betting to 10bb with a hand. If the fish calls, and let’s be honest, fish tend to call 3bets liberally, it would be a 2 SPR pot (~20bb in the middle and 40bb effective). A 2 SPR pot doesn’t leave a lot of room for running double barrel bluffs and is pretty much at commitment, so we would want to use a hand range that would perform well in that 2 SPR pot. Hands like QQ, KK, AA, and AK come to mind…and you can certainly consider hands like TT and AQ as well.
Now what about a more typical spot, one where villain opens to 3bb and has a 100bb stack to start the hand? Well now if we 3bet to 10bb and he calls we are in a 4.5 SPR pot (~20bb in the middle and 90 effective). This is a pretty typical SPR to contend with in a 3bet pot and our “automatic stack-off” ideas can change per player type. Against a fish we are more likely to automatically stack off AK on an Axx board or overpairs , simply because fish will stack-off with plenty of worse hands.
But would a TAG stack-off with QQ on a Kxx board when we have AK? Or take JJ to the felt on a T85 board? This isn’t to say that a fish will never hit a set and win our stack when we stack-off in a 4.5 SPR pot with AA…but overall we expect the stack-off to be profitable in the long run. The fish would have actually made a huge mistake by getting involved in an “automatic stack-off” SPR with a weak hand, even though he’ll suck out occasionally.
Here are some general SPR tips:
1. Be aware of the SPR you are creating: Before you even make your preflop action, consider the SPR it would create and how profitable that SPR would be. Many players get involved too liberally in small SPR pots with suited connectors & small pairs…hand types that want large SPRs going into the flop.
2. Consider your sizes: When 3betting & 4betting your size can greatly influence the SPR. Against inelastic players you can just choose your size and create a more profitable SPR…but against better players you also need to think about how your preflop sizes would influence their range.
3. Fish & SPR: Our SPR ideas can change between fish and regs. Against fish it is more common to stack an overpair in a 4.5 SPR as a default, whereas always doing that against a reg can be dangerous. You don’t want to loosen your SPR standards too much, but they certainly will loosen to an extent against fishy players.
4. Lines can change: Just because you are in a small SPR and you have a stack-off hand doesn’t mean that you have to shove or bet yourself. You can 4bet with AA and create a small SPR and still check the flop. Of course, make sure that your line capitalizes on your opponent’s likely poker mistakes, but don’t feel like you can’t check in small SPR pots.
5. SPR is a preflop/flop metric: Please remember this. SPR tells us if we are committed on the flop, we don’t re-calculate our SPR on the turn and river.
6. SPR is mathematical: You can easily use math to prove the concept of SPR. In smaller SPR pots you can use a fold equity calculator and Equilab to see how often a player would need to fold versus your shoves…and you can go a step further and use Flopzilla to estimate how often a player actually hits.
This hand is from 2NL online, playing four-handed. There’s a limp from the CO, a raise from the Button, who is a 32/21 over 30 hands. Hero decides to 3Bet, which I’m very happy about. However, I think the size here is going to be a major problem.
The issue here is that the size is really small. Typically I’m going to 3bet around 3x the open-raise size at a minimum, which would mean about going to at least $0.30. Against a 32/21, who I’m assuming is not the greatest player in the world, the CO decided to open-limp from essentially the effective UTG. So, I’m also assuming that they’re probably not particularly good. So rather than taking a creative line against a fish, I’m just going to go to a big size here for pure value.
I’d really like to see somewhere in the 40 cent ballpark, personally.
That said, we end up getting called by the Button, go heads up to the flop where Hero bets for $0.36.
Okay, before we really jump into this, I want to back up one quick tick and look at the SPR here. We notice there’s about $0.50 in the middle, about a $1.80 effective, and as such we’re looking at about 3.5 SPR.
My default when it comes to SPR is that I’m going to default stack off my overpairs when it’s less than 3 SPR. Between 3 and 6 is kind of my grey zone, and higher than 6, I don’t default stack off. That doesn’t mean I won’t stack off, just means I don’t stack off as a default.
Obviously, in this spot we’re in the grey zone, but on the smaller side of the grey zone. When I’m in the grey zone against someone who I deem is a weaker opponent, I’m typically still going to stack off my overpairs. In this spot I see no reason not to do that. I think this is a situation where we can still get it in, have an edge, feel comfortable, I don’t think we’re only going to be getting it in against things like sets and two pair. If he has a lot of two pair, then he can have things like JT and T9 that he may very well over-value too.
I’m ultimately feeling very, very comfortable here. My general thought process is I’m going to stack off due to a combination of SPR & how my opponent is likely going to make mistakes; now it’s just how am I going to get my stack in the middle? It’s really important that we understand that and get familiar with playing these kinds of SPRs. When we’re in 3 and 4Bet pots, we’re typically going to be somewhere between 3 to 5 SPR online, so it’s super important that you know how to handle these situations, what goes into it, how to view them, how committed or not committed you are, and then ultimately choosing a +EV line based upon that.
SPR is a simple, yet very powerful concept. It helps us gauge how committed we are to a pot on the flop, which can help us create both preflop and postflop lines. Understand the basic SPR zones, how they influence our preflop ranges, and also how they influence our postflop line creation. As a default, get involved in very small SPR pots with hands you can stack-off profitably, and use implied odd hands in much deeper SPR pots. Remember, this isn’t the only way to use SPR, but understanding the basics is super important!
* SPR was a term first introduced in the book Professional No-Limit Hold ’em: Volume I.