Preflop Raise Sizing: What the Solve Actually Uses

"How much do I open?" sounds like it should have one answer. It does not. The right preflop size is a function of stack depth, position, and the rake or ante structure, and the solve moves it around deliberately. This guide covers open sizing, three-bet sizing in and out of position, squeezes, four-bets and five-bets, why raising beats min-raising, how sizes collapse into shoves, and the common mistakes, with the real sizings the Simple GTO trees use so you can see the pattern rather than guess.

Open sizing

At 100bb, a 2.5bb open is the workhorse. In 6-max cash the solved trees open 2.5bb from most positions at 100bb; in 8-max tournaments the standard open is also around 2.5bb deep. It is a small size because at deep stacks you do not need to risk much to accomplish the open's job, and a smaller size keeps more hands profitable to play by risking less to win the blinds.

But the number is not fixed:

• Position nudges it. Heads-up and blind-versus-blind spots run larger opens than full-table late-position steals, because the dynamics are different with fewer players and worse position. In the cash trees, heads-up opens sit around 2.5bb to 3bb depending on depth.
• Stack depth shrinks it. As stacks get shorter the open compresses. In the cash trees the open steps down toward 2.2bb around 60bb; in the tournament trees it steps from 2.5bb deep toward roughly 2bb around 25bb, because you are risking a bigger fraction of your stack and want to keep the price down.
• Then it collapses. Once stacks get short enough, raising-and-folding stops making sense and the open becomes an open-shove. In the tournament trees the 15bb to 20bb range resolves into a 2bb-or-shove mix, and by 10bb the short-stack opens are effectively all-in.

Rake matters too: in a raked cash game the incentive to end hands preflop is higher, which interacts with sizing and range width together.

Why not just min-raise everything?

A min-raise risks the least, so why is the standard open larger than a min-raise in many spots? Because sizing trades off two things: how much you risk to win the blinds, and how much fold equity and pot control you get. Too small and you invite the big blind to defend nearly anything with a great price; too large and you risk more than the open needs to and start folding out hands you wanted to keep in. The solved size is the balance point for the specific depth and structure, which is why it is a solved output and not a house rule. It is also why the "right" open is smaller deep, where you can afford to keep the pot small, and can grow shorter or heads-up, where denying a cheap flop is worth more.

Three-bet sizing: in position vs. out of position

This is where a single number really breaks down. A three-bet's correct size depends heavily on whether you will have position after the flop.

In the 100bb cash trees, a three-bet in position is around 3.4x the open, while a three-bet out of position is larger, around 4.4x. The logic: position is worth EV, so when you three-bet without it, you use a bigger size to charge the opponent more and make it less comfortable for them to peel and outplay you postflop. In position, you can afford a smaller three-bet because you already hold the postflop advantage.

Squeezing: sizing when players have entered

There is a second wrinkle when players have already entered the pot. Against an open plus a cold-caller, the cash trees add roughly a big blind per caller to the out-of-position three-bet size, because there is more dead money to attack and more players to charge. Squeezing is not the same price as three-betting heads-up, and the solve accounts for it. Under-sizing a squeeze leaves the caller a cheap price to continue and lets the dead money slip away; the extra big blind per caller is what makes the squeeze do its job.

Four-bet and five-bet sizing

The same in-position-versus-out-of-position principle carries up the tree. Facing a three-bet at 100bb in the cash trees, a four-bet in position is around 2.3x the three-bet, while out of position it is larger, around 2.75x, for exactly the reason three-bets are: without position you charge more. From there, the five-bet at 100bb is simply all-in, because the stack-to-pot ratio has collapsed and there is nothing left to do but commit. As stacks get shorter, that commitment point arrives earlier, and four-bet-and-play gives way to four-bet-shove.

Notice the pattern across all three levels: out of position always sizes larger than in position, at every step of the raising war. If you internalize one thing about sizing, make it that.

How antes and shallow stacks change the math

In tournaments the ante changes the incentives around sizing. Because there is dead money in the middle every hand, stealing is more profitable and the open can stay small while still showing a profit, which is part of why 2.5bb holds up deep even as ranges widen. As the stack shortens, the size question stops being "how much to raise" and becomes "raise or shove." That transition is not arbitrary: it happens when your open would commit too large a share of your stack to fold to a shove. The tournament trees map exactly where that line falls at each depth, which is the information a single 100bb chart can never give you.

Limps, completes, and non-standard opens

Not every preflop action is a raise, and sizing thinking extends to the ones that are not. In blind-versus-blind spots the small blind often has a complete (limp) range alongside its raises, and in shallow formats like Spin & Gos the short stacks resolve many spots into a limp-or-shove or open-or-shove decision rather than a standard raise. The Spin trees open around 2bb at the deeper end of the format and collapse toward open-shoves as the stack shortens, which is the same compression you see in tournaments, just faster because the format starts shallow.

You also have to size your responses to opponents who do not use solved sizes. Facing an oversized open, common in live games, you do not just apply your normal chart. A larger open lays you a worse price, so your continuing range tightens and shifts toward three-bet-or-fold, and your own three-bet size adjusts to the new open. The principle is the same as everywhere else in this guide: the number is a response to the exact price in front of you, not a fixed habit. When the open is bigger, everything downstream recalibrates.

Common sizing mistakes

• One size at every depth. Opening 2.5bb at 20bb because you open 2.5bb at 100bb ignores that a short stack needs a smaller open or a shove.
• Same three-bet in and out of position. Using your in-position three-bet size out of position underprices your bluffs and value alike.
• Ignoring extra players. Three-betting the same size over an open-plus-caller as over a lone opener leaves dead money uncontested.
• Guessing the four-bet. Four-bet sizing is not a feel decision; it is tied to position and depth just like the three-bet.
• Raising into shove territory. Continuing to min-raise-fold at a depth where the solve wants an open-shove hands your stack away a chip at a time.

Sizing at a glance

A rough map of the numbers above, all from the solved trees, so you can see the shape at once:

• Opens: about 2.5bb at 100bb in both 6-max cash and 8-max tournaments; heads-up cash runs a touch larger, around 2.5bb to 3bb. Cash opens step toward 2.2bb around 60bb; tournament opens step toward 2bb by 25bb.
• Short-stack opens: in tournaments the 15bb to 20bb band becomes a 2bb-or-shove mix, and by 10bb opens are effectively all-in. Spin & Gos, starting shallow, hit that compression earlier.
• Three-bets (100bb cash): around 3.4x in position, around 4.4x out of position, plus roughly a big blind per caller when squeezing out of position.
• Four-bets (100bb cash): around 2.3x in position, around 2.75x out of position, with the five-bet going all-in.

The through-line is simple: out of position is always larger than in position, and every size compresses as the stack shortens until it turns into a shove.

The point: sizing is part of the solve

Raise sizing is not a house rule you bolt onto a range. It comes out of the same solve as the hands. A chart that lists which hands to open but not what to open to, at each stack depth, is missing half the strategy. That is why the cash ranges and tournament ranges map the sizings across every stack depth alongside the hands: opens, three-bets IP and OOP, four-bets, and the transitions into shove territory.

If you want the sizings for every format and depth in one place, the Master Bundle has the complete set.