Hey everyone,

wasn't sure whether there was a theory thread on opening size but still wanted to ask a few:
- Why are most people opening between 2.0-2.5x?
- How does rake affect opening size (the higher the rake the bigger the opening size?)
- If people are under-3betting, are we supposed to increase our opening size as we are not getting punished as much or should it not change?
- Am I wasting my time thinking about this as opening size does not impact my winrate as much?

My questions apply to 6max cash at micros if anyone wants to answer them

the main reasons for opening are to get value, to isolate and play heads up with a good but vulnerable top-pair type hand, and to get worse hands to call. These factors depend on stakes and villain tendencies and will determine how much you should bet.

6max tends to have smaller openings since the average hand is worse, and there are fewer potential callers. Rake shouldn't impact opening size too much. If the rake is too big, you shouldn't play the game. Otherwise, just play how you normally would. If people are under 3betting, you can open with a wider range. You're never wasting your time thinking about this stuff. Any small change you make to better your game can and should be considered.

EP-4x, MP-3x,CO-2.5x,BU-2x,SB-2x is what use for 6max games

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Poker is all about risk vs reward. If you can risk less for about the same reward that is a win.

It also lets you expand your ranges to some extent because the cost of opening a hand is less with a smaller open size.

Also that size tends to be more popular from later positions because you don't have to worry too much about giving people enticing odds to call behind you since there will be fewer people left to act between your position and the button.


I don't think it would affect your open size directly, but it could affect it indirectly.

As rake rises so does the cost of playing hands. That means some hands become unplayable in high rake games. This means your range should become tighter which should make your range slighty stronger.

If your range is going to be stronger and tighter, then you may prefer a larger sizing especially if other players don't adjust correctly to the higher raked game. It isn't absolutely necessary to raise your betsize though.

It probably shouldn't change based on that quality alone. It may be affected by other aspects of your opponent's play and your adjustment to those aspects.

There isn't much difference between 2 and 3 bb in terms of your overall EV. Most of your EV is going to be dominated by larger pots such as 3bet, 4bet, and jam spots preflop and postflop play where pots are much larger.

As long as you're not opening something like 5+ bb when you RFI for a standard .5bb/1bb structure game you should be fine. Even then it's possible that is a fine sizing based on your strategy and given other factors in the hand/game.

If you want to study betsizing (and you should) it's probably more important to focus on sizing decisions for multiple bets going in on the same street and sizing your bets across multiple streets based on board texture. I wouldn't spend too much time worrying about just your open sizing.

2x from the sb is suicidal. Villain can profitably continue with atc. Don't like 2x from the button or 4x from UTG either.

What do you reccomend?

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The basic theory is that the stronger your range is the smaller you open. Thus in a high rake environment you would tend to open for smaller sizes. But there are other exploitative considerations that might push you in the opposite direction.

I get a fold from BB 28.5% when I open for min with a 50.2% range. My ev is -5.79bb/100 over 8k hands.
I 2x the btn with around 54.5%, get 2 folds around 24.8%. Same sample ev of 51.92bb/100

How can I calculate if I would be better doing a different strategy?


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Your sample is too small. You'd need closer to 500k hands for this.

Ok thx

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I would have thought the higher the rake, the more incentive to win preflop, therefore make raise size larger.

Also, if not being 3b but being called multiway instead, increase raise size. However, if not being 3b, and not being called (a table full of nits) then decrease raise size.

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I think that makes some sense. I believe though that the opponents in the game affect how much post flop you'll see regardless of raise size.

I mean if we were playing with perfect opponents and the rake was high enough there wouldn't be a game at all so if there is a game I don't think you can make the assumption with fairly high rake opponents will respond exactly as you expect with a larger raise size.

I agree though if we're looking purely theoretically that your idea makes sense.

No it doesn't make sense. You don't RFI big with a strong range for the same reason you don't bet pot with top set. You end up pricing out hands you don't want priced out. If you imagine a high rake game where say you're supposed to open UTG 12% and on top of that you open for 3.5x. Well then what sorts of hands do you think the BB can even defend against that? Every other position flatting would be out of the question. The only action you'd see would be 1. getting 3bet by even stronger ranges, 2. BB flatting a very small % with a very strong range.

Of course this all goes out the window when you're playing with bad players who will call junky hands regardless of your 12% range and 3.5x open size. People confuse common exploitative wisdom with what is theoretically correct.

@getmeoffcompletely I basically don't agree with your agrument.

I want to bet as much as possible with the best hands. I only have to bet down when I add worse hands.

I mean taken to the extreme if I only raised AA preflop I would want to raise as much as possible (depending on stacks etc) because my range is so predictable folding could be a better ourcome for me.

It's only when I want to add deception to my range I have to size down becauce betting a huge sizing with other hands is not that profitable.

So overall the open is a balance between getting calls by worse hands for my good hands and not totally screwing my non-good hands on stealing the blinds.

Does anyone have a preflop solver? If so how long would it take to solve for EP opening to 4x with a range of [55+,ATs+,KTs+,QTs+,J9s+,T9s,AJo+,KQo]

Vs opening to 3x or 2.5x

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Perfect play with extremely high rake incentivises pots to be won preflop where no rake is taken. Deep stacks with large pots are favoured where the rake is capped.

Ranges in high rake games will subsequently be stronger and raise sizes on all streets larger.

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I think it's the opposite.

Extremely high rake makes it more likely that the opponents will be playing raise or fold preflop, so it actually makes more sense to open smaller.

I think that is a pretty good argument for a smaller betsize.

- Why are most people opening between 2.0-2.5x?
It`s just more optimal

- How does rake affect opening size (the higher the rake the bigger the opening size?)
The higher the rake the smaller our opening size, in theory. This is because smaller opens are better vs 3bets but worse vs calls. And people should call less in high rake games. Not really true in practice however

- If people are under-3betting, are we supposed to increase our opening size as we are not getting punished as much or should it not change?
That`s actually very smart and correct too

- Am I wasting my time thinking about this as opening size does not impact my winrate as much?
No, understanding as much as you can about poker will make a better player, no matter how useful it seems at first. For example, understanding why opening to 2-2.5x is better than 3+ will allow you to play better against player that open really big. I`d agree that for novice/intermediate players there are better ways to spend their study time however.

I think it's basically ^this^.
High rake (e.g. microstakes) => nittier ranges overall => larger opening sizes.

No/low rake (e.g. in tournaments/high stakes) => looser ranges => smaller sizes.

If you want to play wider than average (e.g. >16% UTG), and want to continue vs 3-bets with a wide range, then a smaller size should be slightly better.
It might have been common to open for 3x or 3.5x UTG back in 2006, but EP opening ranges back then didn't include A5s or T9s. If you want to include weaker hands in your range, then smaller is better.

Provided your ranges are "reasonable", I doubt that choosing a fixed sizing of anything between 2x and 4x is going to affect your winrate much. Most hands are very close to breakeven whatever size you use.

A large size with a tight range and a small size with a wider range can't both be correct strategies in theory. If there are hands which can profitably open for 2.5x but not 3.5x then you should 2.5x, not fold because you've chosen the "tight range, big open" strat. If there are hands that are higher EV at larger open sizes then you should open larger, not smaller because you've chosen the "loose range, small open" strat.

Fixed pre-flop sizing is just a way for humans to avoid complications that arise from forking ranges early in the tree. I don't think there's any theoretical basis for choosing a single sizing or for avoiding 3x+ sizings. I suspect that at NE we would see a variety of sizings used, with a lot of mixing.

But with regard to high rake we want to play less pots and win preflop more often so the larger sizings seem preferred.

I completely agree with browni's second paragraph about using various sizes, but I don't think OP is looking to over-complicate his strategy
A "GTO" computer might use multiple sizes and mixed strategies for the same spot (e.g. sometimes opening for 2.2x with AA, sometimes 5x, or whatever) thus maximizing total EV, but for a human using a fixed size for their strategy I think it's fairly clear that (in 6-max cash* at least), a smaller size allows more hands to be played profitably (or at least moves more combos into the "breakeven" bucket).
In practice, this will mean that a hand like T9s might break even or be slightly +EV if opened occasionally for 2.2x UTG, but it is unlikely to be profitable if opened 100% of the time for 3.5x along with other marginal hands. In short, the smaller size generally allows a wider range to be played, whereas someone playing "tighter than GTO" could benefit from a slightly larger sizing.

* In some short-stacked situations (e.g. in tournaments), the exact opposite is the case. The widest possible range might maximize EV by using a large size (shoving 5x pot for example) instead of minraising.

We have been focusing a lot on absolute bb but it could be possible that relating the opening size to the effective stacksize would be better to generlaizing to other spots?

So when we're saying 2-3.5bb I am assuming we're talking about 100bb effective and thus 2-3.5% of effective stacks is a good opening number.

But a more general way to state it might be x% of your stack given situations y and z.

I might think about this more and expand later if I think my thought process is any good.