SPR (Stack-to-Pot Ratio) is calculated by dividing the effective stack (smaller of the two stacks in play) by the current pot size after preflop betting. A low SPR (1-3) indicates near-automatic stack commitment with medium-high value hands like top pair top kicker. A medium SPR (4-10) requires more calibrated decisions about stack commitment with one-pair hands. A high SPR (>10) favors speculative hands with nut potential, as the implied risk of stack commitment justifies set mining and high-equity draws. SPR is dynamic and should be recalculated each street as bets are made.