5-Bet

Also known as: five-bet, 5bet

The fifth bet preflop — a reraise over a 4-bet, almost always either a premium value jam or a pure blocker bluff-jam.

A 5-bet reraises a 4-bet and, at 100bb, is usually all-in or commits stacks. By this point the ranges are extremely narrow and maximally polarized: the value side is essentially AA, KK, and AK; the bluff side is a thin selection of blocker-driven jams (A5s, sometimes AKo used as a mixed value/bluff hand because it blocks the calling range hard).

The defining feature is stack depth dictating frequency. Deeper than ~150bb you 5-bet more for value and rarely bluff-jam, since the opponent's 4-bet range is stronger and pot odds to call your jam improve. Shallower (≈80–110bb), the 4-betting frequency rises, which means the 4-bettor can be exploited by a tight, blocker-correct 5-bet bluff that folds out their air.

Whether a 5-bet bluff-jam profits is a pure fold-equity equation: with risk \(R\) into pot \(P\), you need folds \(> \dfrac{R}{P+R}\) (adjusted for the equity you retain when called). In ICM spots, the calling stack's risk premium often makes the 5-bet jam more profitable than chip-EV suggests — they must fold more.