SPR (Stack-to-Pot Ratio)

SPR stands for stack-to-pot ratio: the effective stack (the smaller of the two stacks still in play) divided by the size of the pot at the start of a street. It tells you, in one number, how much room there is left to maneuver.

A low SPR (roughly 3 or less) means the pot is already large relative to the stacks, so one pair or an overpair is often happy to get all-in. A high SPR (say 6 or more) leaves lots of room, so you need a much stronger hand to commit and you have more space to bluff or fold. Thinking in SPR keeps you from stacking off too light in bloated pots or playing too passively in deep ones.