Bet Sizing in Poker Part 1

Hey guys. Here is part 1 of my bet sizing series. If you like it don't forget to follow to see part 2.

Why is it Important?

Imagine two opponents engaged in a heads up battle. They play identical ranges; in fact every aspect of their game is identical apart from one key factor - bet sizing. Player 1 is sizing his bets intelligently based on his opponents' range, while player 2 sticks to standard sizings across all situations.

Player one will destroy player two.

Bet-sizing can easily be considered the most underestimated principle that applies to strong NLHE play. It could even be considered the number one thing that sets an average player apart from an elite professional.

We will start with the basics then in the second part of this series we will consider some more advanced principles in relation to effective bet-sizing

Bluffing

The idea behind bluffing is very simple, get the best risk to reward ratio on a bluff. In many cases this means making our bluffs as small as possible, but not always.

There is a very simple method for calculating how often a bluff needs to work in order to be profitable. We simply need to look at the percentage of the total pot we invest including our bluff.

Eg - There is 10bb in the pot. Hero bets 7bb.

Total pot is 17bb including hero's bet. Hero is investing 7 out of the 17bb in the pot. Therefore his bluff needs to work 7/17 = 41% of the time.

It should be reasonably straightforward to establish that the smaller our bluff sizing the less our bluff needs to work. So doesn't this mean that the smaller our bluff the better?
Not necessarily.

The reason for this is that as we change the sizing of our bluff we are also affecting the frequency with which our opponent folds. We might find with our 7bb bet our opponent only folds 20% of the time whereas if we were to overbet our opponent may fold close to 100% of the time. It depends on our opponent, his tendencies, and his range.

One key difference between average players and strong professional players is that they understand when to underbet bluff, when to bet a regular sizing and when to overbet. The average player in NLHE never underbets or overbets, they stick to standard sizings, perhaps 2/3rds pot on the flop. If you are never overbetting/underbetting as a bluff then it's possible to categorically state that you are not reaching your full potential as a poker player.

Value-Betting

Naturally, the idea behind value-betting is to make the most money possible when we have a strong made hand. Often this may mean betting larger but certainly not always. We also need to consider the frequency with which our opponent calls. Sometimes smaller value-bets will make us more money in the long run.

EG. We have the nuts on the river. There is 50bb in the pot. Would we rather
a) Overbet 100bb and get called 5% of the time
b) Bet 30bb and get called 40% of the time
c) bet 15bb and get called 90% of the time

We simply multiply our sizing by our frequency we get called. (We need to express the percentage as a decimal to do this, i.e 40% becomes 0.4 etc)

Therefore
a) 100bb * 0.05 = 5bb
b) 30bb * 0.4 = 12bb
c) 15bb * 0.9 = 13.5bb

So in this particular case underbetting actually makes us the most money because it gets paid off so much more frequently. This is just an example however, overbetting could easily be the best if it gets paid off more frequently.

Common Misconceptions

One of the most destructive pieces of advice that originated in the dark ages of poker - "Bet big on drawy textures, bet small on dry textures". It's not too difficult to see how the advice originated but it's a horrible over-simplification of bet-sizing principles and may cause more harm to our game than good. Here are some reasons why.

Exploiting Inelastic Ranges - We may find on a drawy texture that our opponents calling range does not vary based on our sizing. The technical term for this is an "inelastic" calling range. I.e if opponent has a decent draw he will call, if he doesn't he will fold -regardless of what sizing we make it (within reason). If we bet big in these instances we are simply not getting the best risk:reward ratio on our bluff.

Iso-ing vs Better - When betting for thin value we need to be careful about betting too large and causing our opponent to continue with a range that primarily has us beaten. This means if we have a thin value hand on a drawy texture betting large can easily be a mistake. Keep in mind that it's not always a big deal if opponent continues with a really wide range against us. It just means his calling frequency is higher and we are potentially extracting more value from him in the long-run

Exploiting Calling Stations - If we have the nuts on a dry texture and we are playing vs a calling station there really isn't that much benefit to betting small purely because we've heard that we should bet small on dry textures. If villain will call an overbet on a dry texture because he never folds, then we should overbet for value.

Opponent is Capped - We might be able to define our opponents range as relatively weak. In such instances our opponent may call down small bets on a dry texture whereas he may fold close to 100% of the time when facing an overbet. This is also pretty useful in situations where we are repping a narrow value-range (as is often the case on dry textures), but we will discuss this a little further in part 2 of the series.

Standard Sizings

While we've spent most of the article discussing why weshould not always stick to standard-sizings, it wouldn't be a complete discussion on bet-sizing if we did not acknowledge what the standard sizings are in common situations. It's important because a) we want to know what we are deviating from and b) it can help us to identify weaker players at the table even when we don't have a large sample of stats.
Preflop Sizings
3bet - 3 times the opponents open raise size
4bet - 2.2 times the opponents 3bet size (weaker players make it 3x sometimes)
5b - All-in

Postflop Sizings

cbet in single-raised pot - 2/3rds pot as standard
cbet in 3bet pot - 1/2 pot as standard
cbet in 4b pot - 1/3rd pot as standard (you will see weaker players just making the standard 2/3rds pot cbet here oblivious to the fact they are in a 4b pot)

check/raise on flop - 3 times the cbet (assuming cbet is regular sizing)
3bet on flop - 2.2 times the flop check-raise (a little bit like 4betting preflop)

In part 2 we will look at some more advanced techniques for sizing our bets

A common mistake players make sizing their bets based on the strength of their hand rather than their opponents potential calling range.