Let me start by saying that an entire book has been written about stack to pot ratio, so while I plan to give you a bird's eye view of the concept here, I'm a realist and a pragmatist. If you want to get a solid handle on this advanced concept, it's worth your time to read Professional No-Limit Hold'em: Volume 1 which is co-authored by Matt Flynn, Sunny Mehta, Ed Miller.
What is Stack to Pot Ratio and Why Should You Care?
Stack to pot ratio (SPR) is a calculation you can use in cash games to both simplify and optimize your post-flop decision making.
To calculate your SPR you divide your effective stack sizes by the size of the pot on the flop - and only on the flop. You don't use SPRs in subsequent streets of action.
Don't know about effective stack size? Don't sweat it; a painless explanation is just a click away :)
So, an example:
You're in late position and you call a $10 bet on the flop in a $2/$5 cash game. Both blinds have folded and there is only one other person - the initial bettor - still in the hand. The effective stack size between you and your opponent is $50. Given this information, the stack to pot ratio is as follows:
SPR = 50/27 = 1.85
In other words, the active effective stack sizes are 1.85 times the pot size.
It might also be helpful to think of stack to pot ratios as your risk vs. your reward - the effective stacks being the risk and the pot being the reward.
Practical Applications: How to Interpret Your Stack to Pot Ratio
So you know what SPR is and how to calculate it, but how to you practically use it? As I've already mentioned, your SPR will simplify your post-flop decision making and help you optimize the way you play your hand to maximize your winnings, but I haven't really discussed the best ways to play different SPR situations.
Let's start at the top:
You have a high SPR. (Think 17 or more).
Depending on your hand, finding yourself with a high SPR can make deciding on your course of action challenging. This is because of the relatively large amount of money left in the stacks - money that can be utilized in a number of ways between the flop and river. For this reason, you'll only want to be getting heavily involved if you’re holding pretty solid hands or almost guaranteed draws when you have a high SPR - especially if the hand is getting a lot of action. After all, you don't want to dump a pile of your hard-earned coin in the pot if your chances of getting a return on your investment are practically nil.
As a general guideline, decent hands for high stack to pot ratios are big flushes, high-end straights, solid draws and sets.
You have a mid-range SPR (Think 7-16).
We're entering a little grey area, but we can still negotiate the terrain if we stick to some basic guidelines. If you have a mid-range SPR, stick to flushes, straights, good draws, sets and two top pair if you plan to play big. Even if you go all-in, these hands are generally profitable enough in the long run to keep you out of the red.
You have a low SPR (Think 6 or less).
Having a low SPR basically sets you on easy street as far as strategy goes. There is precious little room to move due to small effective stacks and big pots, meaning you aren't going to need to make many post-flop decisions. Small stacks don't leave room for much fancy footwork, after all. If you have a lower SPR, ideal hands include bottom two pair, top pair or overpairs. Playing these hands with small pots alleviates the chances of taking a hard hit, since you won't be putting as much in the centre. As a result, you can fly with a more mediocre spread.
Remember, there’s a lot more to know about stack-to-pot ratio, and if you’re serious about making poker a profession, you are going to want to learn as much as you can about as much as you can. Still, this article has outlined the foundations to get you off to a good start. Happy playing!