Defense Frequencies

MDF formula explained and how to construct balanced calling ranges.

Minimum Defense Frequency (MDF) is the proportion of your range you must call to prevent an opponent from profitably bluffing with any two cards.

MDF formula

MDF = Pot / (Pot + Bet)
Pot = 100, Bet = 50:
MDF = 100 / (100 + 50) = 66.7%
→ You must call at least 66.7% of your range
Pot = 100, Bet = 100 (pot-size):
MDF = 100 / 200 = 50%
→ Larger bets require less frequent defense

Practical use: MDF tells you when you're over-folding. If you're folding more than the MDF suggests, you're giving opponents a free license to bluff you off every hand. Construct your calling range to hit the MDF.

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