What is the Gap Concept in Poker?
The gap concept was initially introduced by David Sklansky’s classic “Tournament Poker for Advanced Players” and describes a basic poker principle. If someone has already opened with a raise, you need a better hand to call with, than you would need to raise with yourself from the same position.
What is the logic behind the gap concept
There are two main reasons for the gap concept.
Firstly, when you are first to open with a raise, a considerable part of the value of raising comes from the times that your opponents fold, and you pick up the blinds. When you are considering a raise holding marginal hands, this bonus fold equity can shift the balance, making raising a positive expected value move. However, when an opponent has already opened with a raise, the possibility of picking up the blinds is gone.
Secondly, an early position raise narrows the range of your opponent’s hands, unless your opponent is known to have a very loose-aggressive style. As he is opening in an early position, he needs better standards to do so. His minimum requirements are higher than your minimum requirements to raise from a later position. The hands that are in the lower end of your opening spectrum will be in bad shape, even against your opponent’s weaker hands. Against his entire range, that includes the premium hands too, they may be in terrible shape!
The same reasoning is valid even if you do not account for position. Let’s say that your opponent is seated right before you, and your opening ranges are quite similar. Still, your weaker hands do not rate to do well against his full range of opening hands.
Let’s demonstrate this concept with an example.
You are in middle position with A♦10♠ at a full table, and you only have three players left behind you to act. Your ace-ten would be a fine hand to make a raise if everyone folded before you. However, in this example, a player in early position opens with a raise. The other players before you fold, and the action is on you. What should you do?
Well, in this case, the gap principle suggests you should fold! It takes a better hand to call with than what would be an ok hand to open with a raise.
Factors affecting the gap
The gap concept describes this distance between the minimum requirements for raising and the minimum requirements for making a call when someone has already raised. This distance depends on the situation. For example, it takes a better hand to call an under the gun raise than to call a middle or a late raise. When facing an early position raise, the gap distance becomes bigger. This is because in general, when someone raises from an early position, his hand requirements are tighter. As a consequence, there will be a higher percentage of strong hands in his range, and you must adapt your calling range accordingly.
To demonstrate how position affects your calling range, let’s see how the calling range big blind defense against an open raise is affected by the opponent’s position, as proposed in Equilab.
Call vs early position open-raise
Call vs middle position open-raise
Call vs button open-raise
Another factor affecting the gap distance is the opponent’s playing style. If you know that the opponent that raised is tight, you can estimate that his opening range is more conservative. On the contrary, if you know that your opponent is loose-aggressive, you can expect that his opening range is wider. Depending on your opponent’s style, you must adjust your calling requirements. In extreme situations where your opponent is very loose, you may be able to call with the same hands that you would open with. In this case, the gap concept does not apply.
Analyzing two situations
First, let’s consider that you are facing an early position opener that is tight. You believe that he would only be raising with his top 5% hands from under the gun, something like 99+, AJs+, KQs, AQo+.
It is clear that against this range, your ace-ten is in bad shape! Against some of his hands, you are even dominated. So, even if you call and hit your ace, you may find yourself in trouble and risk to lose a lot.
Let’s now consider that the opener is in middle position, acting just before you, and you know that his style is loose-aggressive. From his position and style, you can assume that his opening range is considerably wider, including about 25% hands.
You are in good shape against many of the hands that he would raise with, like ace-high with a worse kicker, king-high, or queen-high hands. In this situation, a call, or even a re-raise can be justified!
In a nutshell
The gap concept implies that you need stronger hands to call a raise with than the hands you can raise with if you are first to open the pot. The gap distance is affected by the position of your opponent and from his playing style. Knowing how these factors affect the gap can allow you to adapt your calling hands in various situations.