3-bet pot
A 3-bet pot is a preflop pot where the initial raise was re-raised before the flop, leaving both ranges tighter and more polarised than in a single-raised pot.
A 3-bet pot begins when someone reraises a preflop open, so the pot has already survived two rounds of aggression before the flop is even dealt. Compare that with a single-raised pot, where one player opens and everyone else just calls or folds.
Because a 3-bet is a bigger, more committal action, both ranges tighten. The 3-bettor is usually repping premium hands or a chosen bluff, and the caller has already decided the hand is worth defending against real strength, so weaker holdings that would flat an open just fold instead. Both ranges end up more polarised, built from strong made hands and playable hands rather than the wide, linear ranges seen after a single raise.
The 3-bet also drags the stack-to-pot ratio down hard, since the extra preflop chips land in the pot before a single postflop card falls.
Worked example. After a 2.5bb open and a call with the blinds folding, the pot is 6.5bb and stacks are 97.5bb, an SPR of 15. After a 3-bet to 8bb is called, the pot is 17.5bb and stacks are 92bb, an SPR of about 5.
That collapse from 15 down to about 5 explains why 3-bet pots play so differently. With so little stack left relative to the pot, top pair and overpairs become far easier stack-offs than they are at an SPR of 15, and one more bet often commits the hand.
Put it to work with the SPR calculator.