Sizing your 3-bets based on hand, opponent, and stack depth
A common theme of this ebook is exploiting your opponent's tendencies given the characteristics of your hand and the situation you are in, and not excessively worry about balance or playing an unexploitable strategy. If you're playing unexploitably, you're not exploiting your opponent. That axiom holds true when sizing 3-bets, as well. To maximize expectation, it is important to vary your 3-bet sizing based on the details of the situation, rather than just using a static 3-bet sizing whenever you go to click the button to re-raise preflop.
1. The specific hand you have matters.
How well does your hand play postflop against marginal middling hands like J8o, Q9o, and 75s? Hands like AK and ATs play poorly against these type of holdings out of position – the ace especially is a very overt part of your 3-betting range and not a big portion of the range your opponent will call the 3-bet with, so your opponent's range plays pretty well against Ax. Hands like KQ, KJ, and premium pairs play much better with smaller 3-bets – you'll get a lot of credit on ace high flops, dominate more of your opponent's calling range, and just generally make it so that your opponent can less profitably call in position.
Even though we are taking advantage of the qualities of our hand, our ranges do not have to be all that unbalanced. We can make bigger 3-bets with big aces, 88-TT, and some bluff hands, which means that we have plenty of hands that are willing to get it in, as many hands as we want that are folding to 3-bet jams, and some hands that play both well and poorly on any flop texture. Similarly, with our smaller 3-bet sizing, we have some hands like KJo and KTs (plus some bluffs) that generally aren't willing to get it in, but also monster big pairs that give our opponent a worse risk/reward price on a 4-bet jam. You can argue that we become marginally unbalanced in certain situations, but for the most part, there will be strong and weak holdings in both ranges, while still taking advantage of the properties of our hand.
2. Your opponent's tendencies matter.
If your opponent is calling a lot of 3-bets, experiment in making your sizings bigger, and see what happens. Even if you are already making it bigger than pot with AKo, and your opponent is now calling in position with insufficient expectation with hands like T7o, it is often worth it to see if they will call bigger sizings as well. We want to charge price insensitive villains as much as they are willing to put in, not just stick to our own informed understandings of what makes for a normal 3-betting size. This goes back to another pervasive theme: Don't just do something that’s profitable, do what’s most profitable. If your opponent is conservative against aggression, smaller 3-bet sizings will often work better, especially with your bluff hands, as your risk/reward calculation gets even more favorable. When you have a value hand against a conservative opponent, you wish your opponent were spewier, but your optimal 3-bet sizing is still unlikely to be more than the size of the pot.
That advice is fairly basic, but when you start to get a little deeper into the specifics, it becomes clear that there is a lot more involved. If your opponent opens wide but rarely 4-bet bluffs (a common default tendency of many regular players), your opponent's range contains a ton of hands that are folding against a 3-bet. Take an opponent who raises 100% of his hands from the button, and assume that a 3-bet to t150 will cause him to continue with the following range:
With any two cards, making this 3-bet is already preferable to folding, even if we were to check/fold every single time postflop! Since clearly we can do much better than that, it shows not just the value of 3-betting wide against a player with these tendencies, but also of making it on the smaller side, especially with bluff hands against a fit-or-fold player.
There are a lot of other tendencies to think about, so this is just to get you started. How often your opponent will 4-bet is often very important in determining 3-bet sizing, which leads well into the third part of this article.
3. The effective stack size matters.
The two important aspects of stack size are how often your opponent will 4-bet, and how well your hand will play postflop if you are flat called. At shorter stacks (less than 25bb deep), hands like big aces tend to just be correct to jam over a minraise, rather than make a non-all-in 3-bet. This only changes when you learn your opponent is willing to 4bet wide, particularly with weak aces and suited connectors, which will generally happen when your opponent suspects you are frequently 3-bet bluffing. At this point, the value from making a smaller 3-bet with AK goes way up, as your opponent may fold A3o to an all-in jam, but 4-bet shove against a non-all-in 3-bet. However, if that is not the case, it is generally a mistake to make non-all-in 3-bets less than 25bb deep with premium Ax hands, and particularly a mistake when the sizing is small, allowing tons of middling hands to correctly come into the pot in position against your holding.
When it is optimal against a player to have a balanced non-all-in 3-betting range less than 25bb deep, it is generally best either to leave yourself with a potsized bet to go all-in on the flop (or c-bet/call all flops comfortably), or a ratio that allows you to continuation bet/fold on the flop if necessary. At deeper stacks, your 3-bet size mostly determines your opponent's 4bet jamming options – whether they can 4bet/fold, and how comfortable they can 4bet jam all-in. Again, this is why a size of 150 can work really well over a t60 open against a wide button opener – it can be really awkward for your opponent to 4-bet bluff given the risk/reward you are offering, particularly when your opponent only knows how to go all-in when making a 4-bet. Few random opponents will know how to make a re-raise to t290 in position as a bluff against this play, and make optimal decisions postflop if flatted.