Minimum Defense Frequency (MDF) Calculator
MDF Calculator
What is Minimum Defense Frequency (MDF)?
Minimum Defense Frequency is the minimum percentage of your range you must defend against a bet to prevent your opponent from profitably bluffing with any two cards. It's calculated as:
If you defend less than this frequency, your opponent can profit by bluffing with any hand.
Common Scenarios
Minimum Defense Frequency (MDF) Calculator: Stay Unexploited & Make Better Calls
The difference between being exploitable and being a tough opponent often comes down to the right frequency of defence — knowing how much of your range to continue with when an opponent bets. That’s what the MDF (Minimum Defense Frequency) concept gives you.
With our MDF Calculator, you’ll enter the pot size and your opponent’s bet size, and instantly see the minimum portion of your range you must call or raise with so that your opponent cannot profitably bluff you with air.
Whether you’re defending the blind, handling a river shove, or sizing up a turn bet, this tool helps you answer: Am I folding too much (or too little) here?
How to Use the VIP-Grinders MDF Calculator
- Enter the pot size (before the bet). This is the “reward” your opponent is wagering you might fold.
- Enter the bet size. How much your opponent is risking to win that pot.
- Hit calculate.
The tool will output the MDF% — the minimum percentage of your range you should continue with (call or raise).
It may also show the corresponding Alpha (α) value, which is the maximum bluff-portion your opponent can profitably use.
Then it is time to apply the result. If your calling-range is wider than the MDF% (i.e., you’re defending more often), you’re safe from too many bluffs. If you’re narrower (folding more), you’re giving your opponent free profit.
- Example: Pot = $100, bet = $50 → MDF = 100/(100+50) = 0.67 → You must defend 67% of your range to deny a pure bluff auto-profit.
Practical Example: River Bet Defence
Imagine you’re on the river. Pot is $150. Villain bets $100.
- Pot size = $150
- Bet size = $100
- MDF = 150 / (150 + 100) = 0.60 = 60%
Meaning: To avoid being exploited by V’s bluffs, you should call or raise with ≈60% of your remaining range. If you call less, V can bluff profitably too often. If you believe V is not bluffing much, you can legitimately defend less than MDF — but you should do so consciously.
Why MDF Matters in poker in 2025: The Strategic Backbone
Preventing Free Bluffs: If you fold too much relative to an opponent’s bet size, they can bluff more freely and earn profit. MDF ensures you defend enough so that those bluffs won’t pay off.
Guiding Your Range Construction: Rather than just asking Do I call this hand?, you ask What portion of my range needs to continue here? This shifts your thinking from individual hands to range defence, an element of advanced play.
When & Why You Might Deviate from MDF
MDF is a GTO-based guideline — it assumes no reads, balanced ranges, and that you want to avoid being exploited by bluffs. In real life:
- If your opponent rarely bluffs, you may defend less than MDF.
- If your opponent over-bluffs, you may defend more.
- Out of position or multi-way pots = MDF may not apply cleanly.
- Boards highly favour one range (e.g.. you have range disadvantage) = you might defend less.
MDF is your baseline; deviations come from reads, position, and range dynamics.
Final Thoughts on MDF Calculator
Use the VIP-Grinders MDF Calculator to back your defence decisions with numbers. When you adopt MDF thinking, you move from reacting to bets to managing your range. You’ll defend the right proportion of hands, avoid giving free money to bluffs, and build confidence in tough spots.
MDF isn’t a rigid rule — it’s your baseline. Use your reads, position, and board context to adjust from it, not ignore it.
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