You would never go into a store and pay more for something than what it is worth would you? Of course you wouldn’t but let us say that you have nothing in a certain pot in NLHE and you want to bluff. In theory, when you bluff, you are purchasing a product and that product is the pot. If we look at a heads-up situation with $20 in the pot and you having nothing on the river! Your opponent checks and there has been no action since the flop.
You decide that bluffing has value and so you decide to have a bet but how big should the bet be? Let us say that you and your opponent have $200 on the table and the stakes are $0.50-$1.00. Now to bet $1 which is the table minimum would be silly. This bet would not only offer your opponent odds of 21-1 but it looks so suspicious that your opponent may even bluff raise you thus causing you to fold. Also any weak hand like bottom pair or even ace high may call simply because they could have the best hand and it is so cheap.
This is clearly not what you want as the bluffer as you clearly do not want a call. So if you don’t want a call then what is wrong with shoving all in for $200? Clearly you will only get called by strong hands but going to the other end of the spectrum is even more of an error. Risking $200 to win $20 is a very poor risk reward and you only have to stumble on a big hand or an opponent that doesn’t believe you or one that plays very poorly like a calling station and suddenly your $200 is history.
If your opponent would fold their junk hand to a $20 pot sized bet then betting $200 is insane as you are taking a needless extra risk of $180 for no possible gain. So between these two extremes of $1 and $200 is an optimal bet size…..but where is it? To better find that out then you need to try and place yourself into the shoes of your opponent and see what you would do against various bet sizes. If you held nothing then you would fold that hand to a pot sized bet of $20.
In fact looking at this situation more closely then your fold would be fairly automatic even if your opponent bet $15. So there is no need to risk needless amounts of money because what you are doing in effect is creating reverse dead money. All of the times when your opponent doesn’t fold and you have bet too much then you have literally wasted money. When you bet $40 as a bluff when a bet of $12 would have been sufficient then you lose $28 every time your opponent is strong enough to call.