Minimum Defense Frequency (MDF)
Minimum defense frequency (MDF) is how often you must continue against a bet so bluffing with any two cards cannot profit: pot ÷ (pot + bet).
Minimum defense frequency, or MDF, is the share of your range you need to continue with (by calling or raising) when facing a bet, so that your opponent cannot make an automatic profit by betting with any two cards. If you fold more often than that, a pure bluff shows a profit against you. MDF is a theory-based guideline that helps you avoid being run over.
The formula
MDF = pot ÷ (pot + bet)
Here "pot" is the pot before the bet. For a 50 bet into a 100 pot: 100 ÷ 150 = 66.7%. You should continue with about two-thirds of your range.
MDF is the flip side of the bluffer's break-even point. That same bluff of 50 into 100 needs folds 50 ÷ 150 = 33.3% of the time to profit, so defending 66.7% denies it that profit.
| Bet size (relative to pot) | MDF | Bluff needs to work |
|---|---|---|
| 25% | 80% | 20% |
| 33% | 75% | 25% |
| 50% | 66.7% | 33.3% |
| 75% | 57.1% | 42.9% |
| 100% | 50% | 50% |
| 150% | 40% | 60% |
| 200% (overbet) | 33.3% | 66.7% |
Worked example: defending on the river
The river board is Q♦ 9♣ 4♠ 2♥ 7♣. The pot is 120 and your opponent bets 60 (half pot). MDF = 120 ÷ 180 = 66.7%.
Suppose, after thinking through the hand, you estimate your range holds about 30 hands (or combos) here. To meet MDF you would continue with roughly 30 × 0.667 = 20 of them, starting with your strongest and working down. If you only continue with 8, a player betting with any two cards wins too often against you.
Note the link to pot odds: calling 60 to win a final pot of 240 needs 25% equity. MDF looks at your whole range, while pot odds look at a single hand.
When to stray from MDF
MDF assumes an opponent who bluffs at a balanced rate. Real opponents rarely do, so MDF is a starting point rather than a rule to follow blindly.
- Against players who rarely bluff, folding more than MDF is usually correct. Calling to "not be exploited" just pays off their value bets. This is exploitative play.
- Against players who bluff too much, defend more often and call wider.
- Earlier streets are different. On the flop, opponents' bets are not pure bluffs; they also have draws, so MDF applies less precisely.
- Your range might simply be weak. If you arrive at a spot with very few strong hands, you may not be able to defend at MDF without calling with hopeless holdings.
Why learn it
MDF gives you a quick sanity check against folding too often, one of the most common leaks for careful players. It also explains why bigger bets can be defended less often, and it is a core building block of GTO thinking.
Frequently asked questions
How do you calculate minimum defense frequency?
Divide the pot before the bet by the pot plus the bet. Against a half-pot bet, MDF is 100 divided by 150, or about 66.7%.
Should I always defend at MDF?
No. MDF is a guideline against balanced opponents. Against players who rarely bluff, folding more often is usually better.
What is the difference between MDF and pot odds?
Pot odds tell you the equity a single hand needs to call. MDF tells you what share of your whole range should continue so bluffs do not profit automatically.
Related poker terms
- Pot Odds — Pot odds compare the cost of a call to the size of the pot you could win, telling you the minimum equity you need for a call to be profitable.
- Bluff — A bluff is a bet or raise with a weak hand that aims to make better hands fold. It wins when your opponent gives up the pot.
- Range — A range is the full set of hands a player could hold in a given spot. Thinking in ranges instead of single hands is the core of modern poker strategy.
- GTO (Game Theory Optimal) — GTO (Game Theory Optimal) is a balanced poker strategy that cannot be exploited: no opponent can gain an edge against it by changing how they play.
- Exploitative Play — Exploitative play means adjusting your strategy to target a specific opponent's mistakes, such as bluffing players who fold too much.
- Overbet — An overbet is any bet larger than the current size of the pot. It's used to apply maximum pressure or to win a big pot with a very strong hand.