Minimum defence frequency calculator
MDF is the share of your range you have to continue with so that a bluff of any two cards stops being automatically profitable.
Not counting the bet you face.
- Minimum defence frequency
- 57.1%
- Maximum you can fold
- 42.9%
- Bet as % of pot
- 75%
- Indifference bluff-to-value ratio
- 0.43 : 1
- Bluffs per value bet that leave a call break-even.
MDF = pot / (pot + bet)
MDF is a heads-up, single-street simplification that assumes the bettor’s bluffs have no equity when called. Treat it as a reference point, not a target — against players who never bluff, folding more than MDF is correct.
What MDF means in poker
Minimum defence frequency is the share of your range you have to continue with against a bet so that your opponent cannot profit by betting any two cards. Fold more often than that and every bluff they make turns a profit, whatever they hold.
The number comes from the bettor’s side of the table. A bluff risks the bet to win the pot, so it breaks even when it works bet / (pot + bet) of the time. That share is usually written α, alpha. MDF is whatever is left over: 1 − α. Defending means calling or raising — any action that does not hand over the pot.
The MDF formula, with an example
MDF = pot / (pot + bet)
Your opponent bets 75 into a pot of 100. A bluff risks 75 to win 100, so it needs folds 75 / 175 = 42.9% of the time. To stop that, you continue with at least 100 / 175 = 57.1% of the hands you arrived with.
- Inputs
- Pot before the bet100
- Bet you are facing75
- Result
- Minimum defence frequency57.1%
- Maximum you can fold42.9%
- Bet as % of pot75%
- Indifference bluff-to-value ratio0.43 : 1
MDF by bet size
Small bets risk little to win the pot, so they force wide defence. Overbets risk a lot, so you can let more of your range go:
| Bet (share of the pot) | Defend at least | Fold at most | Bluffs per value bet |
|---|---|---|---|
| 25% | 80.0% | 20.0% | 0.2 |
| 33% | 75.2% | 24.8% | 0.25 |
| 50% | 66.7% | 33.3% | 0.33 |
| 66% | 60.2% | 39.8% | 0.4 |
| 75% | 57.1% | 42.9% | 0.43 |
| 100% | 50.0% | 50.0% | 0.5 |
| 150% | 40.0% | 60.0% | 0.6 |
| 200% | 33.3% | 66.7% | 0.67 |
MDF vs pot odds
MDF and pot odds look at the same bet from opposite seats. Pot odds give the equity a single call needs; MDF gives how much of a whole range has to continue. Against a pot-sized bet, a call needs 33.3% equity, and the defender has to continue with 50.0% of their hands.
The two meet in the bettor’s balance. If 33.3% of pot-sized river bets are bluffs, a bluff-catcher’s call is exactly break-even — which is where the last column of the table comes from: 0.5 bluffs for every value bet.
Applying MDF to your range
MDF is a share of a range, so it is easiest to use with a count of hands. Say you reach the river with 40 combinations. Against a pot-sized bet you keep at least 20 of them; against a bet of 75% of the pot, about 23.
- Rank the hands by how often they win at showdown against the hands that bet.
- Keep the strongest ones up to the MDF line. Those are your calls and raises.
- Among hands of similar strength, prefer the ones that make it less likely your opponent holds value — cards that block their strongest holdings.
- Fold the rest. Folding them is not a mistake; folding more than these is.
When not to defend at MDF
- Against players who rarely bluff, folding more than MDF is correct: the bet that would punish you never comes.
- Against players who bluff too much, defend more and pick off the bluffs.
- Multiway, the defence is shared. With two players left to act, neither has to defend the full MDF alone.
- Before the river, MDF is only a reference. Bluffs that still have outs need fewer folds, and the hands you defend do not always reach showdown.
If you are on the other side, deciding whether a bluff is worth it, the fold equity calculator prices it from the folds you expect.
MDF across several streets
MDF applies one street at a time, and it compounds. Facing three bets of 75% of the pot, defending exactly MDF on each street keeps 57.1% × 57.1% × 57.1% = 18.7% of your starting range by the river.
That is why ranges narrow so quickly in large pots, and why the hands you keep on the river have to be strong enough to win against the hands that bet three times.
This number covers one spot. PokeAI covers your game.
The calculator answers how much. PokeAI answers why — on the hands you actually played, using this same engine for every number it gives you.
Questions about this calculator
- What is MDF in poker?
- Minimum defence frequency is the smallest share of your range you can continue with against a bet before folding too often becomes exploitable by a pure bluff.
- Should I always defend at MDF?
- No. MDF describes when a bluff becomes automatically profitable, not what is best against a specific opponent. Against someone who under-bluffs, folding more is correct.
- Why do bigger bets lower the MDF?
- A bigger bet risks more to win the same pot, so it needs to work more often. That lets the defender fold more without being exploited.
- What is alpha in poker?
- Alpha is the share of the time a bluff has to work to break even: bet / (pot + bet). MDF is 1 minus alpha, and alpha is also the number of bluffs per value bet that leaves a bluff-catcher indifferent.
- Does raising count towards MDF?
- Yes. Any action that keeps you in the hand defends against the bet. What matters is that you do not fold more than the bet can exploit.
- Is MDF the same as playing GTO?
- No. MDF is one constraint that balanced strategies tend to respect on the river. On earlier streets solvers often defend less than MDF: the betting range is frequently the stronger one, and the hands that call do not always reach showdown.
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