Blog · Strategy
MDF: how many hands to defend against a bet so you can't be exploited
Your opponent bets half pot. You have a medium hand, you hesitate, you fold. On one hand, it doesn't matter. Repeated hundreds of times, it becomes a highway: if you fold too often, any bet becomes profitable against you, even with nothing. MDF, for Minimum Defense Frequency, is the number that tells you where the line is.
The principle: make your opponent's bluff unprofitable
When a player bluffs, they risk their bet to win the pot. Their bluff is profitable as soon as you fold often enough. Example: the pot is 10 BB, they bet 5 BB. They risk 5 to win 10. All they need is for you to fold more than one time in three, and betting any hand makes them money.
MDF is the flip side of that threshold: the minimum share of your range that must continue (call or raise) so that this automatic bluff wins nothing. The formula fits on one line: MDF = pot / (pot + bet), with the pot measured before the bet. In the example, 10 / 15 = 67%: you need to defend at least two thirds of your range.
The table to know by heart
No need to calculate at the table. Five bet sizes cover most of what you'll face. The third column shows the equity a hand needs to call, the logic of pot odds applied to a single hand.
| Bet size | MDF (range that continues) | Equity needed to call |
|---|---|---|
| 1/3 pot | 75% | 20% |
| 1/2 pot | 67% | 25% |
| 2/3 pot | 60% | 29% |
| Pot | 50% | 33% |
| 2× pot (overbet) | 33% | 40% |
Notice how the two columns move in opposite directions. The smaller the bet, the more often you must defend, but with hands that need little equity. The bigger the bet, the less you defend, but every call has to be stronger. A one-third-pot c-bet that you fold to half the time is one of the most expensive leaks at low stakes.
MDF doesn't mean "call 67% of the time"
MDF applies to your entire range, not to the hand you're holding. In practice, you mentally rank your hands from strongest to weakest on this board and continue with the top of the list until you reach the threshold. With the strongest hands you sometimes raise; with the middle you call; with the bottom you fold without regret.
Draws count in your defense, and they're often the best candidates: they have real equity and can turn into semi-bluff check-raises. Conversely, a very weak pair with no draw and no backdoor is the first to leave the range. Texture matters too: on a connected board, your list of continuing hands changes completely compared with a dry board, which is why it pays to properly read the board texture before deciding.
The multi-street trap
MDF is calculated street by street. If you defend 67% on the flop and then 67% of what's left on the turn, only 44% of your starting range remains, and even less on the river. That's normal: every bet filters your range. What you want to avoid is the opposite: defending wide on the flop on principle, then giving up everything that isn't a made hand as soon as the second bet comes. You've then paid into a bigger pot only to fold in the end, the worst possible combination.
So the right question on the flop is: "with this hand, do I know what to do if my opponent bets again on the turn?". If the answer is always "I fold", the hand is probably a fold right now, even if it technically sits in the top part of your range.
When to deviate from MDF (and in which direction)
MDF is an equilibrium point, not an obligation. It protects you against an opponent who bluffs at the right frequency. As soon as you have a reason to think that's not the case, you adjust. The four most common situations:
Your opponent doesn't bluff enough
MDF assumes an opponent who bluffs at the right frequency. At micro stakes, many players bet big mostly when they have it — especially on the river. Against them, defending MDF means paying off a hand that beats you too often. Folding more than MDF is then the profitable adjustment, not a weakness.
Your range is structurally weak on this board
If you called preflop from the BB against a UTG open and the flop comes A-K-x, your range holds far fewer strong hands than the opener's. Theory accepts that you defend a bit less than raw MDF in these spots: the aggressor has the range advantage, and their bets are more often value.
The pot is multiway
MDF is calculated for all the players still to act. Three- or four-way, each individual player can fold far more often: only the collective defense needs to reach the threshold. Defending the full MDF alone in a multiway pot means paying off the bluff on behalf of everyone.
Rake eats the margin
At low stakes, the rake taken from each pot lowers the value of marginal calls. A hand that would be barely profitable to defend without rake often becomes slightly losing. The thinnest defenses are the first to cut.
Preflop, MDF doesn't apply cleanly as is: the big blind already has money invested and plays out of position, two factors that change the defense. That case has its own article on big blind defense.
Using MDF to find your leak
The real use of MDF away from the table is diagnosis. Your Fold to C-Bet gives your actual folding frequency against continuation bets. The glossary entry on Fold to C-Bet places the usual range between 30 and 60%. If you sit clearly above that over a serious sample, your regular opponents have probably already noticed.
The fix isn't to call more at random. It's to identify the hands you give up on too early: backdoor draws, overcards with equity, medium pairs on dry boards. Those are the hands that bring your defense back toward the threshold without making you pay off losing hands.
Frequently asked questions
What is the MDF formula in poker?
MDF = pot / (pot + bet), where the pot is measured before the opponent's bet. Against a half-pot bet, you get 1 / 1.5, about 67%: you must continue (call or raise) with at least two thirds of your range so your opponent doesn't automatically profit by betting any two cards.
What's the difference between MDF and pot odds?
Pot odds tell you how much equity a given hand needs to call. MDF tells you what share of your entire range must continue. The first judges a hand, the second judges your overall strategy. They work together: MDF sets how many hands to defend, equity and pot odds tell you which ones.
Should you always stick to MDF?
No. MDF is the threshold that makes you unexploitable against a balanced opponent. Against a player who rarely bluffs, folding more is profitable; against a player who bluffs too much, defending more is too. It's a reference point to spot a leak, not a rule to apply blindly.
How do I know if I'm folding too much to bets?
Compare your Fold to C-Bet with the MDF of the bet sizes you face most often. If you fold clearly more often than the threshold over a large sample, your opponents can bet any hand against you at a profit. Analyzing your hand history gives you that number on your real hands.
Are you folding too much to bets?
FlopIQ calculates your Fold to C-Bet from your Winamax, PokerStars.FR or Betclic.fr history and tells you whether it's a leak to fix. Your first analysis is free.
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What FlopIQ does on this topic
The FlopIQ tools and analyses that directly address what you just read.
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Fold to C-Bet glossary entry →Big blind defense
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See defense ranges →Pot Odds Quiz
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