Minimum Defense Frequency (MDF)

What is Minimum Defense Frequency (MDF)?

MDF tells you the minimum percentage of your hands you must continue with (call or raise) when facing a bet. If you fold more than this, your opponent can profitably bluff with any hand.

Formula: MDF = pot / (pot + bet). Example: Villain bets 50% pot → you must continue with at least 67% of your range.

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

Why it matters

MDF is derived from making the bettor's bluffs break even (EV = 0) against your folding frequency. If you fold at frequency F > alpha, the bluffer profits regardless of their hand — they can use any two cards.

MDF assumes the bluff has 0% equity. Semi-bluffs with equity reduce the required calling frequency because even called bluffs sometimes win.

Real examples

• Villain bets 67% pot on river: MDF = 60% (must call ≥60% of range)
• Villain bets pot: MDF = 50% (call 1 in 2 hands)
• Villain overbets 2x pot: MDF = 33% (call only strong hands)

Where it shows up

MDF Pressure

Understanding the minimum frequency to defend against a bet.

Common mistakes

Folding Too Much

Folding above MDF makes bluffing automatically profitable for the opponent.

Nuance and caveats

On the flop and turn, MDF is a rough guideline only. The bettor's 'bluffs' rarely have 0% equity — most have backdoor draws or some pair equity.

This means the EV of checking is not 0, which changes the calculation. True equilibrium defense frequencies are computed by solvers and account for the full game tree (future streets, stack depth, runout coverage).

MDF becomes most accurate on the river where hand strengths are finalized.

Key takeaway

Minimum Defense Frequency — how often to defend vs a bet to prevent auto-profitable bluffs.