Stack-to-pot ratios (SPR) are crucial concepts for evaluating the relative strength of different board runouts in poker. SPR refers to the ratio between the effective stacks in play and the current size of the pot. Understanding how SPR changes on various board textures allows you to assess their relative danger and playability.
SPR is calculated by taking the effective stack size and dividing it by the pot size. For example, with $100 stacks and a $20 pot, the SPR is 100/20 = 5. As the pot grows on each street relative to the stacks, the SPR shrinks.
Lower SPRs indicate pots where stacks are shallow compared to the pot size. These runouts require greater aggression and lower SPRs tend to favour all-in manoeuvres. High SPRs denote deeper stacks and more manoeuvrability.
SPR and Board Texture
The SPR of a runout is highly dependent on board texture. For instance, a monotone or straight board will often lead to more betting and raising as big draws develop. This shrinks SPR quickly and creates a more dangerous runout as play continues.
Conversely, a dry, rainbow board likely won’t lead to much pot growth relative to the stacks. This sustains a higher SPR which favours skilled post flop play over all ins.
Assessing how SPR trends over the course of a hand provides great insight into strategic play. A hand may start deep with a SPR of 8 on the flop. But a series of raises on a wet turn and river may shrink it down to 2, changing dynamics considerably.
Recognizing these trajectories allows you to adjust your strategy accordingly and not keep playing a deep stacked game when the board texture has changed things.
Balancing Ranges Based on SPR
You’ll need to adjust your bet sizing and balance your ranges differently based on SPR trends. On drier boards that maintain higher SPRs, smaller bets favour skilled players. But on lower SPR runouts, bigger bets to set up all-ins become preferable.
As SPR drops below 3, equilibrium strategy tends toward a polarized shoving or folding approach. You can capitalize on players who fail to adapt to shifting SPRs.
Playing Lower SPR Textures
As SPR drops below 5, hand values condense since stacks are now short. There are much fewer semi-bluffs or marginal holdings to play around with. Equities run close, so it’s critical to squeeze out as much value from big hands as you can before SPR drops too far.
Don’t fall in love with draws or speculative holdings when the SPR math starts to dictate a more gambly game.
Mastering how to assess runouts through the lens of SPR will make you a much sharper, adaptable player. You’ll develop an intuition for when textures warrant an aggressive, exploitative style versus a balanced, controlled approach based on the SPR trends in a hand.