Effective stack = minboth players' stacks, key metric for post-flop decision-making. Includes SPR relationship, examples, and FAQ.
Effective stack is the smaller stack among the two parties involved in the pot. Post-flop all-in can only win up to the smaller stack portion, therefore SPR, implied odds are both calculated based on effective stack.
Determines SPR, implied odds cap, and whether you can cover an all-in. For multiway pots, take the shortest stack still in the pot. Consistent with the "effective" concept in m-ratio and push-fold. Under ICM pressure, "effective" also includes the constraint of the payout structure on risk-taking. Use the calculator on this page to instantly compute break-even win rate, then compare the numbers with opponent ranges, position, and turn/river plans. Avoid knowing only the formula but not applying it at the table. Common Misconceptions Thinking in terms of 200bb when facing a 40bb cover opponent. The side deep stack makes you fantasize about implied odds, but the main opponent is short. Under ICM, still using physical chips ignores the payout pressure. Also, do not treat solver frequencies as gospel without checking pot odds; when information is incomplete, ICM and SPR are still the first principles of tournaments. Learning Suggestions For each hand, note "vs whom effective XXbb". Tie it to SPR and bankroll. With a short effective stack, switch to push-fold or commit, avoid meaningless floats. Each week, pick five real hand histories and recalculate using the same tool, then revisit the glossary to review concepts such as pot odds, ICM, SPR, etc., which are automatically linked. Cross-referencing with push-fold and MDF helps build a complete preflop and postflop mathematical framework faster.
Scenario：You are 200BB deep, opponent 40BB, pot already built.
Conclusion：Short stack all-in decisions are based on 40BB effective, not your 200BB.
Scenario：Prize jump from $500 to $800, you are medium-stacked facing an open shove.
Chip EV may justify call 2. ICM will significantly tighten marginal calls. 3. Context: Tool example step: effective-stack
View the chip value curve against the distribution tool
Conclusion：During a large pay jump, prioritize survival, unless your hand is clearly ahead of your opponent's shove range.
Scenario：
Conclusion：In the orange/red zone, apply push/fold tables rather than standard defend frequencies.
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GlossarySPR
The ratio of the effective stack size to the current pot size, used to assess commitment levels and post-flop play.
GlossaryImplied Odds
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GlossaryAll-In
The core meaning is that the player stakes their entire stack, forcing opponents to choose between calling or folding. …
ToolsEffective stack ÷ pot, postflop commitment threshold