Ask what size to open and you will usually be told to min-raise. That advice comes from solver work on deep-stacked games against opponents who defend correctly, and in those games it is right. Raising 2bb risks less to win the same blinds, and against a thinking opponent the smaller size does not fold out much less.
The pools most people actually play in do not defend correctly. They call. Once that is true, the reasoning behind the small open stops applying, and copying it costs money quietly for a long time before anyone notices.
So the honest answer is a split rather than a number.
What the open is trying to do
An open-raise has two possible jobs and they want different sizes.
The first is to take the blinds now. Against players who fold too much, this works often enough to be profitable on its own, and the cheapest size that gets the fold is the best one. Risking 2bb to win 1.5bb beats risking 3bb to win the same 1.5bb.
The second is to build a pot with a hand and a range that are ahead. Against players who call too much, nobody is folding regardless, so the first job is off the table. What you are left with is putting more money in while you hold the better hand, and that argues for a bigger size.
Work out which job you are doing at that table, then the number follows.
Deep stacks against opponents who fold
At 100bb or deeper, in a pool where the blinds defend reasonably and 3-bet at sensible frequencies, open to 2bb to 2.5bb. From late position you can go to the bottom of that range because the blinds have to defend wide against a small size and you have position on them for the rest of the hand.
This is where the min-raise advice is genuinely correct. Keep the pot small, keep your range wide, and let position do the work postflop.
One condition to watch: the small open only stays profitable while your postflop game is good enough to play the bigger, wider ranges it creates. If you open 30% of hands from the button at 2bb and then fold every flop you miss, the size is not the problem, but it is making the problem more expensive.
Shallow stacks
Below 50bb the calculation changes and the small size becomes close to mandatory. Opening 3bb at 40bb effective commits a much larger share of your stack, and it leaves an awkward stack-to-pot ratio if you get called.
The original version of this article called a 3bb open at 50bb a beginner mistake, and on that point it was right. At those depths, 2bb to 2.2bb keeps your options open and stops you building pots you cannot get away from.
Club-app pools, where the advice flips
This is the part most sizing guides get wrong for the games our players actually sit in.
In a loose-passive pool, a 2bb open from early position routinely gets three callers. You have not folded anyone out, you have built a four-way pot with a raising range that was designed to be heads-up, and you are out of position in it. That is not a small edge, it is a losing structure.
Against that field, open larger: 3bb to 4bb from early and middle position, plus roughly one big blind for each player who has already called. The larger size does two things. It thins the field, which is worth more than the extra chips risked, because your hand's equity holds up far better three-handed than five-handed. And when they call anyway, which many will, you are in a bigger pot holding the better range.
The same logic runs through everything else you do against these pools, including how you play low limits generally: when nothing folds, stop optimising for fold equity and start optimising for value.
A worked hand
100bb effective, 9-handed cash in a club app. The table has four players calling more than 45% of hands preflop. We are UTG with AhQd.
Open to 4bb, not 2.5bb. At 2.5bb this hand plays four ways and AQo loses most of its value multiway, because the hands that continue against us are pairs and suited connectors that flop well against a broadway.
Two players call rather than four. Flop comes Qs 9h 4d. We bet 60% and get one caller. Turn is the 2c, we bet again.
The point is not the postflop line, which is straightforward. It is that the larger open produced a three-way pot with top pair and top kicker instead of a five-way pot where the same hand is a liability. The chips risked preflop bought a better structure, and the structure is where the money was.
What this looks like in our clubs
Across the apps we run clubs in, the sizing mistake we see most is a good player importing a chart from a training video made for a tougher pool. They min-open, get four callers, and conclude they are running badly.
Fields differ between apps in ways that change the right number. PPPoker tables at low and mid limits run loose and passive, so larger opens do well. The Suprema pool plays looser and more aggressively, which means the same large open gets 3-bet more often, and there you want a tighter opening range rather than a smaller size.
Watch how many players see the flop with you, over a session rather than a hand. If it is consistently more than two, your open is too small for that table.
Frequently asked questions
What is the best open-raise size in poker?
2bb to 2.5bb at 100bb against opponents who fold enough, and 3bb to 4bb against pools that call too much. There is no single number that survives both conditions, and picking one without looking at the table is the actual mistake.
Should I min-raise at micro stakes?
Usually not from early position. Micro-stakes pools call far too wide, so a min-raise builds multiway pots with hands that wanted to be heads-up. Open larger and accept that you are sizing for value rather than for folds.
Does open size change with stack depth?
Yes, and it is one of the few places where the direction is consistent. Below 50bb, keep opens small, around 2bb to 2.2bb, because a larger raise commits too much of your stack and leaves you with an awkward pot-to-stack ratio.
Should I use a bigger size from early position?
Against a loose field, yes. Early position is where multiway pots hurt most, since you play the whole hand out of position. Against a tight, aggressive field the standard advice holds and you can open small from anywhere.
Do I add chips for players who already called?
Yes. Add roughly one big blind per caller when you raise over limpers. You are trying to fold out several players rather than one, and the same size that isolates a single opponent will not do it against three.
Where to start
For one session, count how many opponents see the flop after you open. That number tells you more about your correct sizing than any chart, and most players are surprised by it.
If you want to know which of our fields calls widest before you pick where to play, message @supremaunion. The differences between the apps we hold unions in are larger than the differences between most sizing charts, and they matter more.
18+. Play within your means.