What Is a 4-Bet in Poker?

A 4-bet is the second re-raise before the flop: one player opens, another 3-bets, and the 4-bet raises that 3-bet. It is the point where preflop stops being cheap — a 4-bet usually commits close to a fifth of a 100bb stack and turns the hand into a shove-or-fold decision two streets early. Ranges that 4-bet are therefore narrow and deliberate: strong value hands plus a small, chosen set of blocker bluffs.

How a 4-bet plays out

Size the 4-bet off the 3-bet, not off the original open. In position, roughly 2.2 times the 3-bet is standard; out of position, closer to 2.5 times, because you want less money behind and fewer profitable calls when you have to act first on every street.

Say you open the CO to 2.5bb with A♠K♠ in a 100bb game and the BTN 3-bets to 8bb. You 4-bet to 18bb. If the button folds, you pick up 9.5bb without seeing a flop. If they call, the pot is 37.5bb with 82bb behind — a stack-to-pot ratio near two, so one continuation bet leaves you playing for the stack.

Spot	Open	3-bet	Typical 4-bet
In position, 100bb	2.5bb	8bb	17-19bb
Out of position, 100bb	2.5bb	11bb	25-28bb
Under 40bb effective	2.5bb	8bb	all in

What a 4-betting range holds

Value comes first. AA and KK 4-bet everywhere, AK 4-bets in most spots, and QQ sits on the line — a comfortable 4-bet against a loose 3-bettor, often a call against a tight one, because the hands that continue against a 4-bet are exactly the ones that beat it.

Bluffs are chosen by blockers, not by hope. A♠5♠ and A♦4♦ remove combos of AA and AK from the other player's range, which makes the fold more likely, and when they do call you still hold a wheel draw and a nut flush draw. Offsuit trash makes a poor 4-bet bluff: the same fold equity story, far worse when it gets through to a flop.

Keep the mix value-heavy at deep stacks — you are risking a lot to fold out hands that were folding anyway. Bluff never and observant opponents continue with QQ+ and AK only, and your aces stop getting paid. The solver-built preflop charts show which combos 4-bet, which call and which fold from each seat.

When calling the 3-bet is better

In position, flatting keeps the 3-bettor's bluffs in the pot. Hands like J♥J♠, A♦Q♦ and K♣Q♣ usually prefer a call: 4-betting them folds out everything they beat and gets called by the range that dominates them. JJ against KK is an 18% underdog, and a 4-bet is an invitation to KK.

Out of position it is closer to 4-bet or fold. Calling a 3-bet from the blinds means a bloated pot with no initiative and three streets of guessing, so the marginal hands are better folded and the strong ones better raised.