Tools
MDF calculator
MDF is the minimum share of your range you must continue with against a bet so the bettor cannot profit by bluffing any two cards. It equals pot / (pot + bet).
Type in the pot before the bet and the bet size to get the share of your range you must defend, and alpha, the bluffer's break-even fold frequency.
Inputs
Pot before the bet, and the bet villain makes into it.
MDF · must defend
66.7%of your range
Alpha · can fold
33.3%bluffer's break-even fold rate
defend 66.7%fold 33.3%
MDF by bet size
Common bet sizes into a pot of 100, from the minimum defence frequency article.
| Bet size | Bet as % of pot | MDF (must defend) | Alpha (can fold) |
|---|---|---|---|
| Third pot | 33% | 75% | 25% |
| Half pot | 50% | 66.7% | 33.3% |
| Two-thirds pot | 67% | 60% | 40% |
| Three-quarter pot | 75% | 57.1% | 42.9% |
| Pot | 100% | 50% | 50% |
| Overbet, 2x pot | 200% | 33.3% | 66.7% |
Common questions
- What is minimum defence frequency (MDF) in poker?
- MDF is the minimum share of your range you must continue with against a bet so the bettor cannot profit by bluffing any two cards. Defend less than this and a pure bluff automatically becomes profitable against you.
- How do you calculate MDF?
- MDF equals the pot before the bet divided by the pot plus the bet: MDF = pot / (pot + bet). Against a half-pot bet into a pot of 100, that is 100 / 150, so you must defend about 66.7% of your range and can fold the other 33.3%.
- What is alpha and how does it relate to bluffing frequency?
- Alpha is the complement of MDF: bet / (pot + bet). It is the bettor's break-even bluffing frequency, the rate at which a bluff must work for betting to show a profit. A half-pot bet needs to work about 33.3% of the time; a pot-size bet needs 50%.
- When should I deviate from MDF?
- MDF assumes the bettor bluffs at the optimal rate, which most opponents do not. Against players who under-bluff, defend less than MDF and fold more, since the bluffs you would be catching are not there. Against players who over-bluff, defend wider. Use MDF as your baseline in review, then adjust it deliberately once you have a read.
MDF is the range-level mirror of pot odds, which apply to a single hand. See the pot-odds calculator to check what equity a specific hand needs to call.
Study and review tool. Not for use during live online play.