Preflop 3-bet Sizing

Many months ago I wrote a long post about sizing preflop 3-bets, which after glancing over probably is a mix of good and bad advice. I'm going to take another shot at it today, as I think it is an area where a stakee needs improvement.

Consider a $10NL, with 100BB effective stacks. In general, we are 3-betting preflop either for value or as a bluff. Our sizes obviously need to be consistent between the two. When three betting for value, we want our raise size to be big enough to deny small pairs odds to set-mine profitably against us. This usually means our opponent should have to commit ~10% or more of their stack to call. If they are only getting 8-10:1 on a call with a small pair, calling is certainly -EV for them. That said, we don't want to make our 3-bets so huge that we lose more than we have to when bluffing.

With those points in mind, I typically size my 3-bets as follows (with 100BB effective stacks, more on this later). Against a 3x open raise, I 3-bet to 13x. Villain has to call 10BB, which makes set mining -EV. Against the more common 4x open raise, I 3-bet to 15x. Villain has to call 11BB, which again makes calling with small pairs unprofitable.

Finally, we must adjust our 3-bet sizes to the effective stacks in the hand. If our opponent and ourselves are both 150BB deep, we should 3-bet more than usual. Raising a 4x preflop raise to 18-19x in this scenario is not unreasonable. Conversely, if we are playing with 50BB effective stacks, raising a 4BB raise to 10BB is likely optimal, as our opponent calling with pairs smaller than our 3-bet range is now -EV for him due to stack sizing.