SPR 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. SPR was a term introduced in the book Professional No-Limit Hold ’em: Volume I and stands for stack-to-pot-ratio. Here is the 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 X hand. Let’s look at an example:
100NL No Limit Hold’em – 9 players
Hero (BB): $134.45
Pre Flop: Hero is BB with A A
1 fold, EP raises to $3, MP1 calls $3, 5 folds, Hero raises to $11, 1 fold, MP1 calls $8
Flop: ($25.50) 6 5 2 (2 players)
At this point the effective stack is $50.5 (villain’s stack is the smallest stack) and the pot is $25.50. So the SPR is $50.50/$25.50 = 1.99. This is a very small SPR and is a more common SPR in 4bet pots or 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 if we CB and he shoves, we are calling. If we checked and he shoved, 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 TP+, 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 obviously 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 setmine 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 multi-street 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:
- 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.
- 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 the range they continue with.
- 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.
- 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.
- 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.
- 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 PokerStove 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 the flop.
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!