MDF

MDF (Minimum Defense Frequency) is the minimum portion of the range a defender must call or raise to avoid being trivially exploited by bluffs. It is the core concept on the defensive side of GTO, complementing pot odds.

Detailed Explanation

Formula:

MDF = 1 - (bet / (bet + pot))

Example: pot 100, opponent bets 50.

MDF = 1 - (50 / 150) = 67%

This means the defender must call or raise with at least 67% of their range, otherwise the opponent profits by bluffing with any hand (fold equity is too high).

Relation to pot odds: they are two sides of the same math:

• Pot odds: the minimum equity the caller needs
• MDF: the minimum range share the caller needs

For a 1/2 pot bet:

• Pot odds: 25% (caller needs ≥ 25% equity)
• MDF: 67% (caller needs ≥ 67% of their range to call/raise, keeping the opponent's bluff frequency at most 33%)

Practical applications of MDF:

• Auditing your fold rate: if your fold rate far exceeds 1 - MDF, the opponent profits cbetting any hand
• Designing the check-call range: MDF determines how many bluff-catchers you need to call with
• Defending against an aggressive opponent: when their cbet frequency is very high, your defense should approach MDF

Caveat: MDF assumes the opponent is a GTO player. In real games, MDF is replaced by the opponent's actual bluff frequency — if they cbet 80% but only 5% bluffs, you don't need MDF: you can over-fold without being exploited (and instead exploit their over-cbet).

Common Use Cases

• Designing river calling ranges: MDF as the baseline, then adjust by opponent type
• Identifying your own leaks: in your database, check whether your fold-to-cbet far exceeds 1 - MDF
• Multi-street defense math: every street has its own MDF, and stacking them tightens the total range significantly
• Studying GTO: MDF is the bridge from pot-odds thinking to GTO thinking