Minimum Defense Frequency – Use MDF to Balance Your Calling Ranges

In any single poker session, you face dozens, if not hundreds of bets from your opponents across different betting streets of different hands.

Knowing how to correctly answer to these bets is the difference between strong poker players and amateurs who only play when they have the strongest hands.

In more recent times, poker pros have been using software called poker solvers to help them generate a new poker strategy based in mathematics. This strategy is called game theory optimal, or GTO.

Minimum defense frequency (MDF) is a big part of the GTO poker strategy. It describes the percentage of hands in your range you must continue with when facing a bet in order to remain unexploitable.

In this article, we will explain the concept of minimum defense frequency and teach you how to use it in your games. By the time you are done reading, you may just start thinking about your defending ranges a little differently.

How Does MDF Work in Poker?

Anytime you are faced with a bet or raise in poker, you must make one of three decisions. You either fold, call, or raise.

If you were to fold every time, your opponents could exploit you by betting every time. This way, they would win every pot.

If you were to call every time, your opponents could exploit you by only betting when they have strong hands and checking their other holdings.

Every player out there knows they should fold their trash and continue with their strongest hands when facing bets, but what about everything in the middle?

The concept of MDF, which poker solvers use to decide what hands to continue with, revolves around bet sizing and ensuring your opponents’ bets aren’t exploiting your tendencies.

For example, when faced with a small bet of 1/3 pot, MDF suggests you should continue with 75% of all poker hands in your range. This may seem high, but the logic is quite sound.

If you were to only call or raise 50% of the time against a 1/3 pot bet, your opponent could simply bet every time and print money, as you simply fold too often.

By using MDF, you make the lives of other players at your table miserable, as they can no longer run over you by simply firing bet after bet.

So how do you decide what percentage of your range you should continue with? Let’s take a look at the way MDF calculations are made by the poker solvers.

Calculating Poker MDF

Now that we know what MDF is in poker, it’s time to talk about calculating it, so you can use it in your games.

The MDF calculation is quite simple:

• MDF = Pot Size / (Pot Size + Bet Size)

So, if we imagine facing a $50 bet into a $150 pot, the calculation would be:

• MDF = 150 / (150 + 50)
• MDF = 150 / 200
• MDF = 0.75

Multiply the result by 100, and you get your MDF. In this case, the MDF is 75%, the same number we discussed in the previous section when talking about a 1/3 pot bet.

You can use the same formula to calculate the MDF for every single bet size. This allows you to quickly calculate what percentage of your range you should continue with.

Next, you must decide which of your hands you want to keep in there, and which to fold. However, before we talk about that, here is a quick look at a table that outlines the MDF percentages against common bet sizes in poker, for your convenience.

Choosing the Hands to Continue With

If you look at any solution produced by a poker solver, especially when facing a small bet, you may see it continues with many hands that don’t seem to have a direct connection with the board.

This is because solvers use the concept of MDF and always ensure they are not being exploited. If MDF suggests they must continue with 75% of their hands, solvers will choose the 75% hands with the highest equity to call or raise with.

When you play poker, you won’t have the luxury of having a poker solver break down the range for you, but you can use your understanding of poker equity and intuition to decide which hands to continue with.

First off, you will continue with all your strongest hands, the ones that even an amateur player would know not to fold.

If the bet is on the smaller side, you will need to continue with most of your draws as well, including all gutshot straight draws and hands with overcards.

If this still doesn’t give you enough poker combos, you can start adding hands with backdoor draws to your continuation range.

Remember, the smaller the bet is, the less frequently you should be folding. Constructing your continuing ranges on the fly will never be perfect, but getting close to perfect will make you virtually unexploitable by any human opponent.

Using MDF in Your Poker Games

So, how do you use MDF in your poker games to help you get better results? The truth is, you will not be able to construct perfect MDF ranges in-game, so what do you do?

Whenever you face a bet in your games, you should think about MDF as your baseline. In a predictable fashion, the smaller the bet, the more of your hands you should continue with, and the MDF formula can tell you how many exactly.

Once you have figured out the MDF percentage, you can start thinking about what hands you have in your range, and which ones you can fold to remain unexploitable.

Of course, all of this is only a concern when playing against competent players who are actually looking to exploit you.

For instance, if you are playing in your local home game, chances are players aren’t looking to bluff as often as they could, which means you don’t actually need to adhere to the MDF.

In some extreme cases, you may even be up against players who almost never bluff, which would make defending the MDF range quite inferior to simply folding most of your range.

Yet, when faced with an unknown player or one you know to be solid, you should play close to the MDF strategy when facing bets.

You won’t be able to break down your range as delicately as a solver, but running some MDF simulations in preparations for your games will give you a pretty good idea of what hands solvers typically like to defend with.

How Far Should I Deviate from MDF?

While minimum defense frequency is amazing for creating a perfectly balanced range to face bets with, there are many times when you will want to deviate from it.

Namely, when facing less competent players, you won’t need to defend as wide as MDF suggests, because they simply won’t bluff you enough.

In such cases, you should deviate from MDF and fold some hands that the solver would suggest calling with. But just how many do you fold?

This depends entirely on how unlikely your opponent is to be bluffing. If you are playing against a very tight player who only bets when they have it, you can go as far as to bluff the majority of your range even to a relatively small bet.

On the other hand, if you are facing a more competent player who will fire bets with all their drawing hands, you will still have to call quite often to prevent them from running you over.

Deviating from MDF, like deviating from any other GTO range, requires some fine tuning and delicate adjustments, which can only be made once you understand your baselines quite well.

Simplifying with Pot Odds

Unlike minimum defense frequency, which is a newer term associated with GTO poker, pot odds are a well-known idea in the poker world that most players are comfortable with.

If you are not yet accustomed to playing poker the GTO way, using pot odds to decide when to call the bets is another solid way of going about things.

The ranges of hands that solvers come up with when using MDF can be confusing to less experienced players, which is why pot odds can be a much more intuitive way of thinking about countering your opponent’s bets.

Whenever you face a bet, simply calculate your pot odds, and proceed with hands that have enough equity against your opponent’s perceived range.

For example, if you face a half-pot bet, you should continue with all hands that have 25% equity or more. Think about your opponent’s range and decide if your hand has enough equity to continue against it.

You can learn more about calculating your pot odds in our guide to poker odds, and use the strategies from that guide to simplify your decisions when faced with a bet.

Do I Need MDF in My Poker Game?

MDF, like all other GTO poker concepts, is a fairly advanced strategy that is best used in tough games and against difficult opponents.

While you won’t necessarily have to apply MDF to beat your low-stakes poker game, adopting this concept in your poker game will set you on a course of thinking about poker the right way.

If you have the desire to learn poker on a high level and eventually play against stronger players, MDF is one of the concepts you will need to understand.

Start learning about MDF with the help of poker solvers today, but remember you can also use pot odds to simplify your decisions against the vast majority of players.

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