Minimum Defense Frequency (MDF)
What is MDF?
MDF (Minimum Defense Frequency) is the minimum percentage of the time you must defend (call or raise) against a bet to prevent the opponent from making an auto-profitable bet (auto-bluff).
If you fold too often, the opponent can profitably bet with any hand, even complete air.
Formula
MDF = Pot / (Pot + Bet Size)
- Pot — size of the pot before the opponent’s bet
- Bet Size — opponent’s bet amount
MDF shows how often you need to continue to avoid being exploited.
Examples for Common Bet Sizings
| Bet Size | MDF (Minimum Defense) | Fold Frequency |
|---|---|---|
| 0.25 pot | 80% | 20% |
| 0.33 pot | 75% | 25% |
| 0.5 pot | 66.6% | 33.3% |
| 0.66 pot | 60% | 40% |
| 1 pot | 50% | 50% |
| 1.5 pot | 40% | 60% |
| 2 pot | 33.3% | 66.6% |
Practical Application
- MDF is a GTO tool — it does not guarantee a profitable call, but prevents giving away free EV.
- Helps to:
- Defend your range optimally
- Check if you are overfolding
- Plan range frequencies: how much to call vs raise
Example
Pot: 100 bb
Opponent bets: 50 bb (0.5 pot)
MDF = 100 / (100 + 50) = 0.666 = 66.6%
You must continue (call or raise) 66.6% of the time to deny them an auto-profit bluff.
Important Notes
- MDF applies to your whole range, not to a specific hand.
- Exploitative play: vs opponents who rarely bluff, you can fold more often.
- GTO approach: if you have no reads, stick to MDF.
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