Your remaining stack divided by the pot.
The lower it is, the easier it is to get all-in, and to commit with one pair. Example. With a 5.5bb flop pot and 97.5bb behind, the SPR is about 17. In a 3-bet pot, 92bb against a 17.5bb pot is about 5, and with an overpair or top pair strong kicker you can get your stack in even when raised. In PLO, a single-raised pot with a pot-size open has an SPR of 12-13, a 3-bet pot about 3.5, a 4-bet pot about 1, and after a pot-size bet and a call it becomes (SPR − 1) ÷ 3.