Minimum Defense Frequency (MDF) Calculator
This MDF Calculator computes your minimum defense frequency, Alpha (bluff break-even frequency), and pot odds for any bet sizing in seconds.
Enter the pot size before the bet and your opponent’s bet size to see exactly how wide you need to defend.
MDF Calculator
What is Minimum Defense Frequency (MDF)?
The difference between being exploitable and being a tough opponent often comes down to the right frequency of defense. This means knowing how much of your range to continue with when an opponent bets. The MDF (Minimum Defense Frequency) concept helps you with that. It's calculated as:
If you defend less than this frequency, your opponent can profit by bluffing with any hand.
Common Scenarios
How to Use This Calculator
The calculator needs two inputs. Here is what each one means and how to read the output.
Enter the pot size
This is the pot before your opponent bets. If the pot is $100 and your opponent has not acted yet, enter 100.
Enter your opponent's bet size
The amount your opponent bets into the pot. A half-pot bet into a $100 pot would be 50. A full-pot bet would be 100.
Read your results
The calculator returns three values: MDF (the percentage of your range you must defend), Alpha (the fold frequency at which your opponent's bluff breaks even), and pot odds (the equity your specific hand needs to call profitably).
What Do the Results Mean?
Each result answers a different question about the spot you are analyzing. Here is what to look for.
Minimum Defense Frequency (MDF)
MDF tells you what percentage of your total range must continue when facing a bet. If you fold more often than 100 minus MDF, your opponent can bluff with any two cards and profit automatically. Defending at or above MDF keeps their bluffs break-even at best.
This is a range-level metric. It does not tell you whether one specific hand should call. Pair MDF with an equity calculator to decide which individual hands belong in that defending range.
Alpha (Bluff Break-Even Frequency)
Alpha is the inverse of MDF and the two always add up to 100%. It represents how often you need to fold before your opponent’s bluff becomes profitable. A half-pot bet has an Alpha of 33.3%, meaning their bluff prints money the moment you fold more than a third of the time.
Use Alpha when you are the one considering a bluff. If you expect your opponent folds more often than Alpha, your bluff is profitable regardless of what you hold.
Pot Odds
Pot odds measure the price a single hand is getting to call. The calculator shows this as the minimum equity your hand needs to make calling correct long term. For a half-pot bet the threshold is 25%. For a full-pot bet it is 33.3%.
Pot odds and MDF answer different questions. Pot odds evaluate one hand, while MDF evaluates your entire range. Use our pot odds calculator when you need to decide whether a specific holding justifies a call.
MDF (%)
The share of your range you must continue with (call or raise) to stop your opponent from auto-profiting with bluffs.
Alpha (%)
The fold frequency at which your opponent's bluff breaks even. Fold more than this and every bluff prints money.
Pot Odds (%)
The minimum equity a specific hand needs to call profitably. Compare this to your hand's estimated equity.
MDF Reference Chart
Use this table for quick lookups when you do not have the calculator open.
| Bet Size (% of Pot) | MDF (%) | Alpha (%) | Pot Odds (%) |
|---|---|---|---|
| 10% | 90.9% | 9.1% | 8.3% |
| 25% | 80.0% | 20.0% | 16.7% |
| 33% (1/3 pot) | 75.0% | 25.0% | 20.0% |
| 50% (Half pot) | 66.7% | 33.3% | 25.0% |
| 67% | 60.0% | 40.0% | 28.6% |
| 75% | 57.1% | 42.9% | 30.0% |
| 100% (Pot-sized bet) | 50.0% | 50.0% | 33.3% |
| 125% | 44.4% | 55.6% | 35.7% |
| 150% | 40.0% | 60.0% | 37.5% |
| 200% (Overbet) | 33.3% | 66.7% | 40.0% |
As bet size increases, MDF drops and Alpha rises, which means larger bets need fewer folds to turn a bluff profitable.
Frequently Asked Questions
What is minimum defense frequency in poker?
MDF is the minimum percentage of your range you must continue with (call or raise) to prevent your opponent from automatically profiting with bluffs. It is calculated as Pot Size / (Pot Size + Bet Size). At exactly MDF, your opponent’s bluff breaks even.
How do you calculate MDF?
Use the formula: MDF = Pot Size / (Pot Size + Bet Size). Multiply the result by 100 to convert to a percentage. For example, a $50 bet into a $100 pot gives MDF = 100 / (100 + 50) = 66.7%.
What is Alpha in poker?
Alpha is the fold frequency at which your opponent’s bluff breaks even. It equals 1 minus MDF, so the two always add up to 100%. For a half-pot bet with 66.7% MDF, Alpha is 33.3%.
Should you always follow MDF?
MDF is your baseline against balanced opponents. Deviate when your opponent bluffs far less than GTO suggests (common at low stakes), when ICM pressure applies in tournaments, or when you hold strong reads on a specific player. For more on balanced versus exploitative play, see our GTO and solvers guide.
Does MDF account for semi-bluffs?
Standard MDF assumes bluffs have zero equity when called. In practice, many bluffs retain equity through draws, which means you may need to defend slightly wider than MDF suggests. Our semi-bluff EV calculator helps quantify that adjustment.