SPR (Stack-to-Pot Ratio) in poker is the ratio of the effective stack to the size of the pot at the time of reaching the flop. It is one of the most important post-flop parameters, determining how deeply you can play in a hand, which bet sizings make sense, and which lines are available at all.
SPR Formula
The calculation is simple: SPR = Effective Stack / Pot Size. The effective stack is the smaller of the two stacks (yours and your opponent’s) at the time of reaching the flop. If you have 100bb, your opponent has 80bb, and the pot has 7bb after the pre-flop action — SPR is 80/7, or approximately 11.
The higher the SPR, the deeper the post-flop play: more streets of pressure, more room to maneuver. The lower the SPR, the more “compact” the post-flop: decisions become binary, maneuvering options are minimal.
Types of SPR
Low SPR (1–3): quasi-commitment zone. With top pair or better on the flop, it typically makes sense to go all-in in some way. Medium SPR (4–9): the standard range for most post-flop situations. Both draws and made hands have room. High SPR (10+): deep-stacked play where speculative hands gain full value. Implied odds and multi-street pressure become crucial.
SPR in Single-Raised Pots
Standard open of 2.5bb, one caller, pot = 5.5bb. With effective stacks of 100bb, SPR ≈ 18. This is a very deep SPR — position, draws, and multi-street ranges all matter enormously. Compare: a 3bb open with a fish calling, pot = 7bb, effective stacks 40bb (short-stacked fish) — SPR = 6. A very different post-flop game.
SPR in 3-Bet Pots
A 3-bet pot (e.g., BTN opens 2.5bb, BB 3-bets to 9bb, BTN calls) — pot = 18.5bb, effective stacks ≈ 91bb after calling. SPR ≈ 5. This is a medium SPR — made hands (sets, two pair) are close to commitment, strong draws are playable as semi-bluffs with significant fold equity.
SPR in 4-Bet Pots
4-bet pots (e.g., BTN opens 2.5bb, BB 3-bets 9bb, BTN 4-bets to 22bb, BB calls) — pot ≈ 44.5bb, effective stacks ≈ 78bb. SPR ≈ 1.75. This is nearly pre-commitment: on any pair+ or draw the stacks go in, and fold equity is minimal. Pre-flop range selection here is critically important.
How SPR Affects Strategy
With low SPR: value bet wide, slow-play less (there’s no depth to maneuver), play draws as semi-bluffs, commitment is easy. With high SPR: more selective with value bets, pot control with medium-strength hands is important, drawing hands gain value through implied odds, multi-street ranges matter more. The correct bet sizing also depends on SPR: with SPR = 2, a half-pot bet on the flop sets up a natural all-in on the turn; with SPR = 15, the strategy must account for 3–4 streets of action.
SPR and Hand Type
Draws prefer high SPR — more streets to realize equity and collect on implied odds. Made hands (sets, two pair) prefer low SPR — easier to get all the money in before draws can arrive. Medium hands (top pair weak kicker) perform best at medium SPR with pot control.
Common SPR Mistakes
- Ignoring SPR and playing the same line regardless of depth
- Over-commitment with marginal hands at high SPR
- Failing to re-size opens to achieve a more favorable SPR
- Treating SPR as an absolute rather than as a contextual guide
- Not adjusting drawing hand strategy based on SPR
Example Hand with Different SPR
You hold A♠K♦. Board: A♥7♦3♣. Pot 10bb, effective stack 100bb (SPR=10) — pot control on flop, thin value on turn, evaluation on river. Same hand, SPR=2 (25bb stack, 13bb pot) — bet-fold is the correct line, quick commitment with top pair top kicker. The same hand requires different strategy based purely on SPR.
SPR and Open Sizing
Pre-flop sizing controls the SPR you create. Opening larger (3.5–4bb instead of 2.5bb) creates a lower SPR in called pots, which makes it harder for callers to play drawing hands. Opening smaller creates higher SPR and favors speculative hands. This is a deliberate pre-flop adjustment that professional players make based on stack depth and their hand type.
SPR and Opponent Analysis
Understanding SPR helps build exploits against specific opponents. A player who doesn’t understand SPR will often over-fold with marginal hands at low SPR, or over-commit with top pair at high SPR. These are recognizable patterns in tracker data that can be systematically exploited.
SPR is a fundamental concept that connects pre-flop decisions with post-flop strategy. Mastering it allows making correct decisions faster and more consistently, based on a clear structural understanding of the spot.