SPR and the Bar to Stack Off

Whether a hand is worth stacks is mostly a question about geometry, not about the hand. Each pot-sized bet forces your opponent to defend roughly half their range. Pot the flop, pot the turn, pot the river, and the range that calls all three is 50% of 50% of 50%: about 12.5% of what they started the flop with. To value bet that line you need to beat the majority of that top 12.5%, which is an enormous bar. Top pair does not clear it. Most two pairs do not clear it.

Now shorten the stacks. With one pot-sized bet left, your opponent defends more than half, partly because you are jamming hands with equity and they cannot be raised off anything, and the range you must beat is around the top 60%. With half pot twice getting all in, they defend about two thirds each street, two thirds of two thirds, so you need to beat roughly the top 44%. Same cards, same board, three different verdicts, decided entirely by how much money is behind. This is the theory underneath an intuition most players already half-own: top pair is a fine stack-off shallow and a money fire deep.

Depth also reshapes when you bet. Deep, a hand that cannot value bet three streets often should not start betting early at all, unless range considerations demand it. Check the early street, let bluffs in, and collect on the turn and river against a range that stayed wide. And when you do want stacks in deep on a static board where you hold the nut advantage, spread the bets geometrically, the same fraction of pot on each street, which is how the money gets in without any single bet becoming an over-the-top shove. Shallow, none of this urgency applies, because modest bets already commit the stacks by the river.

The failure mode this math kills is the fixed gauge: deciding "top two is a stack-off" once and applying it at every depth. Before the flop even arrives, the stack-to-pot ratio has already set the bar your hand will have to clear, and reading it takes one glance. The bet sizing reference shows how solve sizings shift with depth and texture, and the 80/20 river rule covers the threshold the whole ladder works back from.