What is a Solver in Poker? How Solvers Work & How to Think About Them

A solver is a powerful piece of poker software that calculates ‘optimal’ strategies (called solutions) for user-inputted scenarios. The most commonly used solvers include PioSolver, GTO+ and Simple Postflop.

Solvers have changed the game since they became commercially available in 2015, raising the standard of play significantly.

A solver’s solutions contain a lot of valuable insights, but how exactly do solvers work? And is it worth your time to try and remember everything the solver does so you can replicate its strategy?

This article will help you understand the answers to these crucial questions and more.

Note: You can learn how to use a solver like a pro to improve your poker skills with the PioSOLVER Crash Course inside the Upswing Lab! Learn more now!

How A Solver Works

Let’s start off with how a solver works in a general sense.

In short, solvers calculate an optimal strategy based on a handful of options (inputs) which are set by the user. These options are:

• The preflop ranges of each player
• Bet size options
• Raise size options
• The effective stack size
• The size of the pot
• Donking/leading possibility

These inputs make a solver’s strategic output quite abstract. In a real game of No Limit Hold’em, you can’t possibly know your opponent’s exact preflop range. You also don’t have such a limited number of bet/raise size options, and leading out is always an option. And yet, the solver bases it’s output on these constraints.

You could say that solvers don’t actually solve No Limit Hold’em. But they do solve pieces of No Limit Hold’em, which can help you better understand the underlying mechanics of the game.

(Note: If you use solved preflop ranges in conjunction with solvers, you can actually get relatively close to the true Game Theory Optimal (GTO) strategy.)

There is one more important aspect that you need to keep in mind about a solver’s inner-workings…

The solver operates under the assumption that each player knows the other player’s complete strategy from preflop until the river. It is based on that assumption (plus the constraints listed above) that the solver comes up with an unexploitable (i.e. equilibrium) strategy.

So, if a solver’s solutions are abstract, what good are they? That’s the subject of the next section.

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How Should You Think About Solvers?

A solver is like a magic genie. You get exactly what you ask for — nothing more, nothing less. If you ask the wrong question (i.e. screw up your inputs), you may not get a useful answer.

In order to get accurate and useful strategic outputs from the solver, your inputs need to be as close to reality as possible. Once you figure that out, you should try to understand why the solver plays certain hands the way it does. (Or at least why playing a certain hand a certain way adds value to the overall strategy.)

When you understand why the solver plays the way it does, you will start to identify patterns/concepts. Since you can’t possibly expect to study every possible flop, turn and river in the solver, internalizing patterns/concepts for the ones you do study is critical.

What types of patterns and concepts am I referring to?

Provided that you don’t screw up your inputs, here are a few types of patterns you can learn from a solver output:

• Betting/raising range morphology (i.e. which hands you should bet/raise).
• Global frequencies (i.e. how often you should bet/check/etc)
• Which hands should be played with a mixed strategy (e.g. checking sometimes while betting the rest of the time)

With these outputs in mind, you can begin your exploration into figuring out the why behind them.

For example, in a past article I explored when to check on the flop with overpairs. I ran a bunch of different situations and flop textures through PioSolver and found that checking on very connected and middling flops (such as 9♠ 7♣ 5♥ or 7♣ 5♥ 4♦) was the solver’s preferred action with most overpairs.

Here’s a solver screenshot from that article showing the high frequency checking strategy with overpairs (button vs big blind, single raised pot on a 9-7-5 flop):

So, what’s the why behind the solver’s strategy?

These connected flops are great for the big blind because he has so many straights and two pairs in his range. The solver responds by playing more defensively with overpairs.

Additionally, the highest overpairs are checked more frequently than the lower overpairs (i.e. AA was checked more often than JJ). This is because the lower overpairs benefit more from protection since there are more potential overcards that can come on the turn.

Both of these concepts hold true on the vast majority of very connected, middling flops. This is a great example of how you can discover valuable trends by studying a relatively small group of flops in a solver.

Wrapping Up

To sum up (and for those of you who were to lazy to read the whole article):

• A solver doesn’t actually solve No Limit Hold’em
• It gives the right answer to the question it was asked (that doesn’t mean it was the one you were looking for)
• Your inputs need to be very close to reality
• Focus on understanding why the solver takes the lines it takes
• Use the nodelock function to experiment with different strategies and take note of how the solver adjusts

Now that you know how solvers work, this article will be a valuable read for you: How to Dominate Ace-High Flops in 3-Bet Pots (Deep Analysis).

Till’ next time, good luck, grinders!

Note: Ready to join 6,000+ players currently upgrading their No Limit Hold’em skills? Crush your competition with the expert strategies you will learn inside the Upswing Lab training course. Learn more now!