Probe bet
Betting into the preflop raiser on the turn after they checked back the flop. Their check capped their range, and the probe attacks the cap.
The cutoff raises, you call in the big blind, and the flop checks through. The turn comes and you bet. That is a probe: a lead into the preflop aggressor after they have declined to continuation-bet, and it is one of the most reliably profitable bets available to a player out of position.
The reason is what their check told you. A player who opens preflop and then checks the flop is almost never holding a strong hand — with top pair or better they would have bet, because betting is how those hands make money. Their range is capped: middling pairs, ace-high, and a lot of hands that missed entirely. Against a capped range, a bet on the turn wins immediately far more often than it should, and the hands that do call are usually the ones you can read on the river.
Sizing follows the same logic. Because you are attacking weakness rather than protecting equity, a probe does not need to be large — a third to a half of the pot takes the pot down often enough and keeps the price of being wrong low. On boards where the turn card favours you specifically, larger works.
The mistake is probing indiscriminately. Some opponents check back the flop with strong hands deliberately, and against them the probe walks into a raise. And on a board where the checked flop hit their range anyway — ace-high, king-high — the check is more likely to be a trap or a slowplay, so the range is not as capped as the general rule suggests.
FAQ
What is a probe bet in poker?
A bet made into the preflop raiser on the turn after they checked back the flop. Their decision not to continuation-bet caps their range, so betting into it wins the pot immediately far more often than a normal bluff would.
How big should a probe bet be?
Small is usually enough — a third to a half of the pot. You are attacking a range that has already shown weakness, so the bet does not need to charge draws or protect equity, and a small size keeps the cost of the times it fails low.
When should you not probe?
Against opponents who deliberately check back strong hands, and on boards where the checked flop favoured them anyway — ace-high and king-high flops. There the check is as likely to be a trap as a surrender, and the range is not really capped.