If you’re serious about mastering ICM play, this article introduces rMDF – a risk-adjusted framework that redefines how you calculate defence frequencies under ICM pressure. Built for advanced players and grounded in solver logic, this is the practical bridge between theoretical MDF and real-world tournament survival. Whether you’re deep on the bubble or navigating final table dynamics, rMDF gives you a sharper, more disciplined approach to defence.
Minimum Defence Frequency (MDF) is a cornerstone concept in Game Theory Optimal (GTO) poker, especially when analysing whether or not to continue facing a bet. While it is well understood in cash games or chipEV tournament stages, MDF must be reevaluated under the Independent Chip Model (ICM) during high-leverage spots like the bubble or final tables.
Here we will explore how MDF is calculated, why it changes under ICM pressure, how to study and apply it effectively through real hand examples (see bonus material at the end of the article), as well as provide you with a simplified model for in-game decision-making rMDF (Risk-Adjusted MDF).
What is Minimum Defence Frequency (MDF)?
MDF is the percentage of your range you must continue with (by calling or raising) when facing a bet to prevent your opponent from profitably bluffing with any two cards.
MDF= POT SIZE / (POT SIZE + BET SIZE)
Example:
- Pot = 100 chips
- Villain bets 50 chips (half pot)
- MDF = 100 / (100 + 50) = 0.667 or 66.7%
You must defend the top 66.7% of your range to avoid being exploited.
MDF Cheat Sheet (ChipEV)
| Bet Size | MDF % |
|---|---|
| 0.25 X POT | 80% |
| 0.33 X POT | 75% |
| 0.50 X POT | 67% |
| 0.66 X POT | 60% |
| 0.75 X POT | 57% |
| 1 X POT | 50% |
| 1.5 X POT | 40% |
| 2 X POT | 33% |
Why MDF Changes Under ICM
ICM introduces a major shift in how we evaluate risk. Unlike chipEV where each chip has equal value, under ICM chips lost hurt more than chips gained help. Survival becomes more important than chip accumulation. As a result, players can and should fold more (MDF decreases). Bluffing becomes more profitable for chip leaders while calling becomes more dangerous.
Calculating MDF under ICM pressure
There is no simple one-size-fits-all formula to calculate MDF under ICM, because the calculation depends on stack distributions, pay jumps, and relative positions. However, solvers with ICM modelling like GTO Wizard, simulate ranges using expected value (EV) loss in chips converted to tournament dollars (chipEV – $EV).
The ICM-adjusted MDF values provided in the cheat sheet below are estimates derived from solver outputs. They reflect a conservative defence strategy under pressure, assuming standard final table and bubble dynamics.
ICM-Adjusted MDF Cheat Sheet
| Bet Size | Bubbe | FT (Early) | FT (ICM Pressure) | FT (HU) |
|---|---|---|---|---|
| 0.25 X POT | 60% | 65% | 55% | 75% |
| 0.33 X POT | 55% | 60% | 50% | 70% |
| 0.50 X POT | 45% | 50% | 40% | 65% |
| 0.66 X POT | 40% | 45% | 35% | 60% |
| 0.75 X POT | 38% | 42% | 32% | 55% |
| 1 X POT | 30% | 35% | 25% | 50% |
Introducing Risk-Adjusted Minimum Defence Frequency (rMDF)
To help players navigate ICM-heavy situations, I propose a simplified yet effective heuristic – rMDF. This model offers a practical way to adjust MDF calculations in real time when ICM pressure skews traditional decision points rather than memorising charts.
The Concept:
- Risk Premium (RP): An estimated penalty for ICM pressure, ranging from 0.10 to 0.50 depending on your relative stack and payout pressure.
- Larger RP means more ICM pressure – defend narrower ranges.
Examples:
- Facing a half-pot bet: standard MDF = 67%
- On the bubble with medium stack: RP ≈ 0.30 – rMDF = 67% × (1 – 0.30) = 46.9%
- Heads-up (RP ≈ 0): rMDF = standard MDF = 67%
Why use rMDF?
- Helps bridge solver study and real-time intuition
- Reinforces stack-awareness and pay-jump discipline
- Guides defence against ICM abuse without memorising charts
This model is not a solver-derived formula but an original, conceptual framework designed to simplify the application of ICM pressure in MDF reasoning. Using it helps you train better habits and decision-making heuristics.
MDF vs. rMDF Under ICM Pressure Sheet
| Spot | MDF % | RP % | rMDF% |
|---|---|---|---|
| ChipEV Spot (No ICM) | 50 | 0 | 50 |
| Early FT vs CL (Hero 2nd stack) | 50 | 8 | 58 |
| Bubble spot (Hero covers short) | 50 | 10 | 60 |
| Bubble spot (Hero is short stack) | 50 | 15 | 65 |
| 4 left, even stacks | 50 | 5 | 55 |
BONUS MATERIAL: Studying MDF Under ICM
Example 1: Bubble Spot
- 10 left, 9 paid. You’re mid-stack. Big stack shoves from BTN into your BB.
- ChipEV: You might call with ATo, 66, KJs
- ICM: You may only call with AQ+, 99+, folding hands you’d normally defend
Example 2: Final Table, 5 Left
- Short stack has 6bb, you’re 3rd in chips. CO opens 2x, you’re in BB.
- Normally, you defend KTo, QJo, 87s
- Under ICM, you may fold KTo and QJo to avoid volatile spots
Example 3: Heads-Up
- No ICM pressure exists anymore
- Return to chipEV MDF: defend 50–75% depending on bet size
- Call lighter again: T8s, A2o, Q7s
Study Tips: Practice by reviewing spots in solvers like GTO Wizard with ICM enabled, and compare your decisions to chipEV benchmarks.
Label hands in your study tracker as “Bubble/ICM/FT/Early” to train your intuition for ICM-adjusted defence frequencies.
