Definition of stack to pot ratio
Between any 2 players the stack to pot ratio (abbreviated as SPR) is the smallest stack size remaining in front of either player (known as the ‘effective stack’ between them), divided by the current pot size. Note that the SPR is calculated after a round of betting has been fully completed (whether that be preflop, on the flop, turn, or river).
The higher the stack to pot ratio, the more money or chips behind left that can be played for.
Example of calculating stack to pot ratio
- Let us imagine we are playing a live $2/$5 9 handed cash game.
- The UTG player sitting with $1000 opens to $20, it is then folded to the short stacked button who is sitting with $161. The button calls, and both the blinds fold.
- This means there is $47 in pot just before the flop is dealt (the $20 the UTG put in, the $20 the button put in, the $2 the small blind was forced to put in, and the $5 the big blind was forced put in). The 2 remaining players in the hands have the following amounts left in their stacks: The UTG has $980 ($1,000-$20), and the button has $141 ($161-$20). The effective stack going into the flop is thus $141 (the effective stack between any two players, is the smallest of their remaining stacks – the extra chips the UTG player has compared to the button, cannot be used.
- The SPR is Effective stack ($141) DIVIDED BY the Pot size ($47) = 3
Easy to remember SPR tactics
You can use the Stack to pot ratio, to help you decide whether to stack off with top pair or better (or even worse hands in certain situations), especially when other information is limited. Put another way, SPR can help you decide whether you are committed to the pot, regardless of what happens on future streets.
- Warning: The following are really rough tactics, for when you have top pair or better. You should NOT blindly follow these – always consider all the other information at your disposal and your overall strategy:
- If you have at least top pair, stacking off with an SPR of at least 6 may well be a negative EV play.
- If you have at least top pair, stacking off with an SPR of 3 or less may well be a positive EV play.
- When your SPR is between these amounts, then whether you should stack off might be based upon factors such as board texture, and if playing exploitatively what reads you have on your opponent.
One of the biggest mistakes unstudied players make is they get too attached to their preflop premium hands, in high SPR pots, and just can’t fold their AA over 3 streets. Similarly, another big mistake made by unstudied players is folding their top pair or better hand, in situations where the SPR is too low to justify it (their hand might be winning, and if it isn’t they still have equity versus their opponent(s) range, and the low SPR means they cannot fold)
Different preflop starting hand types prefer different SPRs
- Speculative/drawing hands like small pairs (aiming to make sets), and suited connectors (aiming to make flushes, and straights) would prefer the SPR to be high. This is because drawing hands would ideally like opponents to either fold, or win a bigger pot when their draw comes in. The smaller the SPR, the harder it is to get opponents to fold, and the less you could win if your draw comes in. If the SPR is too small, you might not have the correct odds (neither direct or implied) to proceed in the hand when facing aggressive action from your opponent.
- Premium pairs and premium no-pair starting hands (such as AKo) would prefer a low SPR. The lower the SPR, the easier it will be for you to realize all your preflop hot and cold equity (as an aggressive opponent will find it harder to get you to fold).
Betting decisions & stack to pot ratio
- If your hand/range would prefer a lower or higher SPR, you can use your opening sizes and re-raising sizes to help get to the SPR you want.
- Whether you fastplay or slowly, and your line in a hand, might depend on SPR.
- If you are the out of position preflop raiser in a heads up pot postflop, and the SPR is on the low side and you have a draw – you could consider checking, and then over bet shoving the flop. Whilst with the same flop and draw in a bigger SPR, you might c-bet yourself.
