What is GTO in Poker?

Welcome aspiring Wizards! Game theory optimal is a term commonly thrown around in the poker world. But what does GTO actually mean? Why is GTO important? What makes it “optimal”?

A Brief Introduction to Game Theory

The meaning of GTO in poker is Game Theory Optimal. Game theory is a study of mathematical models of strategic interaction conceived by mathematician John Nash. Its application has shaped the development of poker strategy for the last several years to the point that winning at the highest stakes requires knowledge of GTO principles.

“When people speak of GTO poker, they are referring to a Nash Equilibrium strategy.”

A Nash Equilibrium strategy is optimal because it cannot be exploited. No one can increase their expected value by changing their own strategy. Another term used to describe these strategies is “balanced”.

No Limit Hold ’em is a vast game when you consider all the different hole card combinations for each player, bet size possibilities, and possible runouts, making unexploitable strategies impossible to derive by hand. It’s so large that we may never even know the full game theory optimal solution for deep-stacked games. Even so, with the poker software available today, we can gain a pretty solid understanding of what a GTO poker strategy looks like.

Simplified poker game tree with EV.

How a GTO Strategy Is Found

Using software called “solvers”, we craft and run simulations to collect data on what GTO looks like.

Solvers are powerful computer programs that take as input:

Preflop ranges for the two players.
The board cards.
A target level of exploitability (accuracy).
Starting pot and stack sizes.
The postflop betting structure.

Because there are nearly infinite possible bet sizes and limited computing power, you have to choose a betting structure that provides the solver with enough strategic options to provide meaningful outputs.

Inputting parameters into solver.

Once the simulation has been constructed, the solver iterates on strategies for each player. Each player takes turns exploiting the other. A GTO strategy has been found when it reaches a point where neither player’s strategy can be exploited for more than the target level of exploitability.

Here’s an animation of a BTN (IP) vs CO (OOP) 3BP solving down to nash equilibrium.

First, the strategies vary wildly as both players try new ideas! Then the strategic changes slow down as it progresses towards equilibrium until it finally reaches a point where neither can adjust to exploit the other. Note that this animation was sped up by a factor of about 120x.

Animation of iterated strategies achieving equilibrium. OOP strategy is facing 75% bet.

A Trick Question: GTO or Exploit?

You may have heard players referred to as “exploitative” or “GTO” players. In reality, these two approaches are more like two sides of the same coin than opposing points of view.

If you don’t know what the game theory optimal strategy looks like, how do you know that you’re exploiting your opponent and not being exploited in return? By gaining a deep understanding of GTO, you can play an unbeatable default strategy and pinpoint your opponent’s mistakes.

Poker software like GTO Wizard provides all of these postflop solutions and aggregate reports making it a great tool for studying GTO poker. Looking at all the data generated by solvers and aggregated by GTO Wizard, we know that the game theory optimal strategy will make use of mixed strategies, a variety of bet sizings, and balanced ranges in each situation. GTO Wizard gives you the tools to understand bet size preferences of hands in different situations and how each hand mixes into other bet sizes or more passive lines for the purposes of balance and deception. Studying these solutions and reports will help you train your GTO poker intuition.

Why You Should Study GTO to Improve Your Strategy

Now, how does honing your GTO poker intuition help with developing exploits? Even playing game theory optimal strategies, there are many situations where range asymmetries allow one player to take seemingly extreme action. Classic examples include:

Attacking capped ranges with overbets.
Bluffing all your air against an opponent’s give-up line.
Folding all bluff catchers when your opponent’s range does not contain enough bluffs for their chosen bet size.

“By understanding what your opponent’s range should look like, how your opponent has deviated, and having familiarity with how the solver attacks similar range asymmetries in other situations, you have all the information you need to craft powerful exploitative strategies against your unbalanced opponents.”

To recap:

GTO helps you understand a baseline strategy
Recognizing that baseline helps you know when and how to exploit mistakes
GTO achieves an unexploitable balanced strategy through Nash Equilibrium
GTO doesn’t rely on reads or intuition to make strong plays

An understanding of game theory optimal poker provides the foundation for you to adapt to any situation and maximize your win rate against any competition. In short, by becoming a GTO Wizard, you’ll have all the tools you need to play an unbeatable default strategy and craft powerful counter-strategies after identifying your opponents’ mistakes.