Posted on 2024-09-26

A bulletproof Guide to Preflop Bet Sizes

In the complex world of poker strategy, understanding when to bet preflop is probably the most essential skill, closely followed by how much we should bet.

So once we know our preflop ranges by heart, it is probably a good idea to look at preflop bet sizing. To illustrate the thought process on what variables determine our bet sizes, we’ll follow one example, change different parameters and see if and how these modifications change our sizing.

What variables factor into bet sizing?

For our example we assume a eight handed multi table tournament with a 100 big blinds stack, everyone folds to us, and we wake up with A♥Q♣ in the Cutoff. Given this example, we can already extract some parameters:

• Position: What is our position relative to other acting players in the hand?
• Previous Action: Have players before us already opened the pot?
• Game Type: Is it a cash game or MTT?
• Stack Size: What is our current stack size?
• Hole Cards: What are our hole cards to begin with? (We’ll see later, that this parameter does not change our sizing)

Scenario 1: Raise First In

Say it folds around to us and we are to act. We definitely want to play A♥Q♣, so we open raise. Given the example, we should opt for 2.5 big blinds, which is a good baseline for a 100bb stack. Some players will go for 3 big blinds, which is fine as well, especially in lower stakes. Players in lower stakes tend to be static, meaning they don’t play differently whether they face a 2.5 or a 3.5 big blind raise. While in theory the 3-betting range of our opponents should change depending on our open raise sizing, in reality these marginal amounts don’t do much to manipulate their ranges. So why risk the extra 0.5-1 big blind if it achieves little to nothing?

Scenario 2: Getting 3-bet from the Blinds

One common scenario we will encounter is getting re-raised from a player acting behind us after we opened the pot with our holding. This is where position becomes relevant. Not so much our specific position vs our opponents specific position, but whether we’ll be in position (IP) postflop or not. Sticking with our example setup, we’d be in position (IP) postflop against a 3-bet from the blinds, but out of position (OOP) against a Button re-raise.

After getting re-raised we have the options to fold, call or raise again (4-bet). A♥Q♣ can 4-bet as a semi-bluff against a blind re-raise. Why is this a semi-bluff? We don’t really want to get 5-betted or shoved in this spot, because villains range will be super strong, even more so from the small blind. At the same , we put enormous pressure on villains 3-betting range, since we are IP postflop. So continuing for villain will be very hard.

To bring the right amount of heat, we want to bet 2.5x the amount of villains bet, when we are IP. So let’s run through the example:

• We are in the CO with A♥Q♣ and everyone folds to us
• We open to 2.5bb
• Button and Small Blind fold
• Big Blind raises to 10bb (more on that sizing in scenario 5)
• We do 4-bet as a semi-bluff and raise it up to 25bb

Scenario 3: Getting 3-bet from Button

A more complicated scenario we can face would be a 3-bet from a later position that will have position on us postflop.

Say Button 3-bets us, and we want to 4-bet, what is difference compared to the previous scenario? We’ll be OOP after the community cards have been dealt, since the button has absolute position on everyone postflop. This lowers our equity realization, so we want to pressure Buttons 3-betting range even more. Which is why we’ll increase our 4-bet size to 3x the amount of villains bet, when we are OOP.

Let’s run through our example again:

• We are in the CO with A♥Q♣ and everyone folds to us
• We open with 2.5bb
• Button 3-bets to 7.5bb (more on that sizing in the next scenario)
• Blinds fold
• We do 4-bet as a semi-bluff and raise it up to 22.5 big blinds

Notice something? We ended up moving less chips to the middle of the table when 4-betting out of position than 4-betting in position. Why is that?

When playing IP, villain will be OOP and therefore has to pressure our range as hard as they can with a strong range. When we 4-bet (and since villains 3-betting range has to be relatively strong to begin with), we do so with only our strongest holdings and a few bluffs (A4s or A5s being a premium candidate). Our range is very linear (plus we’ll be in position after the flop), and so we are more comfortable putting more chips into the pot. We choose a smaller raising size (2.5x), so that villain can continue with most holdings that we are likely ahead of.

On the other hand, if we are OOP postflop, villain will have an IP 3-bet range, which is a bit wider and contains more semi-bluffs that we can in turn attack with a wider range. Since villain is IP they choose a smaller 3-betting size, giving us the rope to exert more pressure by choosing a bigger 4-betting size.

So it all comes down to range morphology, a topic we will discuss in a future article as it reveals a deeper idea on why these different betting sizes exist and how bet sizes modulate ranges.

Scenario 4: Facing an open from Middle Position

Facing an open from an earlier position is basically the same scenario as the previous but with reversed perspective. After a raise first in, much like the button in our last example, we decide to challenge that open with a 3-bet. Remember that an open is 2.5bb, and if we were to raise it up like in our 4-bet example (where we played IP), that would mean a raise of 6.25bb. That might be okay, but feels a bit on the passive side. Remember, re-raising is all about bringing the heat to our opponents range, while withstanding that heat ourselves. We also have to account for the Button, Small Blind and Big Blind who all have yet to act. Raising to 6.25bb gives them a good price to join in on the action and call behind, which we definitely don’t want. So we raise it up a bit and choose a 3x multiplier. This reduces the incentive to call behind.

So in our example:

• We are in the CO with A♥Q♣
• HJ before us opens to 2.5bb
• We do 3-bet and raise it up to 7.5 big blinds (like BTN did in the previous example)

Scenario 5: Defending from Blinds

Defending from the blinds is the only spot preflop where we are forced to 3-bet OOP. Since this often occurs after an open from a late position and we’ll be always OOP, we want to pressure villains stealing range as much as possible, so we make it really pricey to continue for them. We choose a wider range of combos to 3-bet with, but our overall 3-betting frequency is lower than 3-betting from IP. This has two effects: We have more holdings to attack the steal with, which makes it harder for villain to continue (remember, villain is in the same spot we were in scenario 2, so they need very strong holdings to put even more money into the pot to pressure our diverse 3-betting range) and the bigger sizing forces villain to fold out most of their opening range.

Let’s see it in our example:

• We are in the BB with A♥Q♣
• CO before us opens to 2.5bb
• BTN and SB fold
• We do 3-bet and raise it up to 10 big blinds

We already know that if villain 4-bets, their range is extremely linear giving us an easy decision. We move all in with our absolute strongest holdings and a small amount of decent semi bluffs and call with more marginal but still strong holdings like AQs, TT, T9s.

Raising bigger OOP exerts pressure on the relatively wide IP opening range, forcing to fold out most of the range.

Scenario 6: Isolating Limpers

Facing a limper is often a double-edged situation. On the one hand it signs a weak player, on the other hand we need a good holding to really attack the weakness. In our situation A♥Q♣ is perfect to attack. But how big should we bet?

If we were to follow the rule of 3-betting IP, we’d raise it to 3bb. Now let’s do some math. There are 1.5bb in the pot to begin with. The limper called the big blind, we raised it to 3bb, so there are now 5.5bb in the pot. The next player gets a decent price to just call behind, with pot odds being 1.81:1 (or 35%). If we raise it up to 5bb, the pot odds drop to 1.5:1, and we need 40% equity.

Changing the Stack Size to 50bb

How does changing the stack size affect all these scenarios? This is where the different game types come into play, because cash games are played at 100bb at least, since we can always add to our stack after going below 100bb. So playing under 100bb is only relevant for MTTs.

Scenario 1: Raise First In

In general the lower the average stack size at the table, the lower our raises should be, because somebody could shove on us relatively easy. If we think about it: Opening 2.5bb with a 20bb stack would mean a IP 3-bet of 7.5bb and a OOP 3-bet of 10bb. At this point the 3-betting player is more or less committed to the pot, and we have to shove if we want to raise, since the pot is already so big relative to our stack and therefore the pot odds or required win equity is quite low. We want to lower our opening size to lose less against the occasional shove and give ourselves more room to act against 3-bets which will be linearly sized to our opening raise. So the lower our opening raise, the lower the 3-bet we’ll face. The table at the end of the article gives us an overview on what opening size to use for different stack depths.

Scenario 2: Getting 3-bet from the Blinds

In this case we are out of position and (depending on our stack) we need to push all-in or bet relatively small. The cutoff is at about 35bb. With more than that we can 4-bet with raising 2.5x, since we are IP and BB has to commit a good portion of their stack if they want to continue.

• We are in the CO with A♥Q♣ and it folds to us
• We open 2.2bb
• BTN and SB fold
• BB 3-bets us and raises it up to 6.6bb
• We decide to 4-bet to 16.5bb

Scenario 3: Getting 3-bet from Button

Having to 4-bet OOP (as we learned in the first section), we don’t have to commit as many chips since IPs 3-betting range is wider, and they use a smaller 3-betting size to begin with. We therefore can go big to exert pressure on their wide range and still end up risking less chips than 4 betting in position. We raise 3x villains bet here in this scenario.

• We are in the CO with A♥Q♣ and it folds to us
• We open 2.2bb
• BTN 3-bets to 5.5bb
• We decide to 4-bet to 16.5bb

Notice that in this specific stack size configuration we end up risking the same amount of chips regardless if we are IP or OOP, but we bring a lot more heat on BTNs range from OOP because we can raise it up 3x instead of 2.5x.

Scenario 4: Facing an open from Middle Position

Short stack play is all about pot control and this skill is essential from the get-go. If we were to 3-bet 3x IP regardless of our stack size, we’d maneuver ourselves into a lot of trouble.

Say we hold K♦J♦ in the CO and HJ raises to 2.2bb with both players having 35 big blinds behind. If we were to raise 3x, that would mean a raise of 6.6bb. HJ 4-bets us for 19.8bb. Now almost 60% of our stack is gone. There is very little room to act and a auto shove looms on the horizon because of the good pot odds we built ourselves. But remember, HJs 4-betting range is very strong and KJs might not be hand we want to shove with.

Let’s find a more decent 3-betting size. If we go for 2.5x, this will result in a 5.5bb and a resulting 4-bet of 16.5bb. This might not sound like much but over the course of a tournament these small savings can buy us a pay jump.

Scenario 5: Defending from Blinds

Defending from the blinds follows the same concept of giving us room to act. We want to lower our OOP 3-betting size depending on our stack depth to not commit ourselves to an automatic all-in with a marginal holding.

Changing our hole cards to A♠5♦

Changing hole cards (that otherwise follow the same strategy) should never lead to different bet sizes. Here’s why:

Let’s go back to our 100bb stack scenario and assume we open our standard opening range from the CO with 2.5bb. But since we are feeling lucky, we also want to play some more marginal hands like off-suited connectors. These don’t perform that well and have to fold against 3-bets. What could we do about it? We aren’t getting 3-betted all the time, but for the case we are, let’s reduce our losses. So we decide to open off-suited connectors with 2bb, every other combo we want to play with 2.5bb. What did we just create? A huge exploitable leak. If any of our opponents is aware of what’s happening at the table, they will attack our 2bb opens like crazy, because we always have to fold to their 3-bets. We are splitting our range into two parts, when changing our opening size based on our holding.

Therefore, we always should play the same spot in the same way, otherwise we will be easily exploitable.

How does Cash and Tournament sizing differ?

As showed in the lower stack size scenario, cash and tournament play starts to differ once our stack depth significantly drops below 100bb. GTO uses very fine-grained opening and raising sizes, but as a beginner it is better to simplify and correctly implement a simplified strategy than to blunder left and right trying to play GTO (which we never will anyway).

What to do against multiple opponents?

Against multiple opponent we’ll need to play a more linear range and at the same time raise it up even more. If there is an opening, others are calling behind, and we want to 3-bet, we should calculate the initial 3-betting size as if there were no other players involved and then add the bets of the players that called behind. For example:

• We are in the CO with K♠K♦
• UTG opens 2.5bb
• HJ calls behind 2.5bb
• LJ calls behind 2.5bb
• We 3-bet to (2.5 x 3) + (2 x 2.5) = 5 x 2.5 = 12.5bb

A hand like K♠K♦ is good against one opponent (especially when we are playing IP postflop), but this premium holding gets massively reduced in value when playing against three opponents. So our goal with this massive raise is to get folds of the opponents that call behind. We want to have one single opponent. Sometimes we’ll lose the initial raiser as well, that’s the game. But we never want to play against three opponents with Kings.

What else determines bet sizes?

There are a lot of factors that play into bet sizing, here are just a few more of them.

Position

Some players vary sizes based on early, mid and late position. As a beginner you don’t need to follow that. It is better to implement a simplified strategy correctly.

Average Stack Size

If we are the chip leader and every other active player behind us is short, we can exert even more pressure by increasing our opening raises and 3-betting sizes. This is a bit more advanced, but can help us steal blinds more effectively.

Betting Sizes Cheatsheet

Stack Size	RFI	Iso Limper	3-bet	4-bet
more than 125bb	3bb	5bb	3.5x IP, 4.5x OOP	3x IP, 3.5x OOP
100-125bb	2.5bb	5bb	3x IP, 4x OOP	2.75x IP, 3.25x OOP
60-100bb	2.3bb	4.5bb	3x IP, 4x OOP	2.75x IP, 3.25x OOP
35-60bb	2.2bb	4bb	3x IP, 4x OOP	2.5x IP, 3x OOP
22-35bb	2.1bb	4bb	2.5x IP, 3x OOP	All-In
12-22bb	2bb	3.5bb	All-In	All-In
less than 12bb	Push or Fold	All-In	All-In	All-In

Sources:

• Modern Poker Theory by Michael Acevedo
• 100 Essential Tip to Master No-Limit Hold'em by Jonathan Little
• Own Solver Work