MDF (Minimum Defense Frequency)
The minimum percentage of your range you must continue with to prevent opponents from profitably bluffing any two cards.
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What Is MDF (Minimum Defense Frequency)?
MDF is calculated from pot odds: it is the pot size divided by the pot size plus the bet size. If a player folds more often than the MDF against a given bet size, an opponent can profitably bluff with any hand, regardless of its actual strength. MDF is a game-theory-optimal defense concept, though real exploitative play often deviates from it based on opponent tendencies.
Examples
Against a pot-sized bet, MDF requires you to continue with at least 50% of your range to remain unexploitable.
The solver's MDF calculation showed she needed to defend 67% of her range against the small continuation bet.
Strategy Tips
Use MDF as a baseline for how often to continue against a bet, then adjust based on your opponent's actual bluffing frequency. Smaller bet sizes require a higher MDF, meaning you must defend a larger portion of your range. Remember MDF describes range-wide defense, not a rule for every individual hand, so weaker holdings within your defending range can still be correct calls. Combine MDF thinking with reads on bet-sizing tells for the most effective adjustments.