MDF (Minimum Defense Frequency)

What Is Minimum Defense Frequency?

Minimum Defense Frequency (MDF) is the minimum percentage of your range you must continue with, either by calling or raising, to prevent an opponent from profiting with pure bluffs. If you fold more often than MDF allows, your opponent can bet any two cards and show an automatic profit, regardless of what they hold.

The MDF Formula

MDF is calculated as:

MDF = Pot Size / (Pot Size + Bet Size)

This can also be expressed as MDF = 1 - Alpha, where alpha is the breakeven bluff frequency. The two concepts are mirror images of the same mathematical relationship.

Common MDF Values to Memorize

• 33% pot bet: Defend 75% of your range
• 50% pot bet: Defend 67% of your range
• 67% pot bet: Defend 60% of your range
• 75% pot bet: Defend 57% of your range
• 100% pot bet: Defend 50% of your range
• 150% pot bet: Defend 40% of your range

These benchmarks are essential for making quick in-game decisions. The MDF Calculator computes exact MDF values for any bet size instantly.

MDF in Practice

MDF is a theoretical guideline for balanced play, not an absolute rule. Against an opponent who never bluffs, you should fold more than MDF suggests. Against a chronic over-bluffer, you should call wider. But MDF provides the default baseline that prevents exploitation when you lack specific reads.

MDF and Bluff Catching

MDF directly determines which hands become Bluff Catching candidates. After ordering your range from strongest to weakest, you continue with the top MDF percentage and fold the rest. The hands at the boundary are your marginal bluff-catchers, the ones that are indifferent between calling and folding against a balanced betting range.

Training Your MDF Instincts

Postflop+ is the ideal training ground for developing MDF intuition. Its GTO bot bets at various sizes across different board textures, forcing you to practice defending at correct frequencies. Over time, MDF-based decisions become automatic rather than calculated.