ICM Calculator Bug Fixed: Fold EV Difference of -2.45 for AKs at 10BB vs 12BB in 50/30/20 Payout Structure
A Reddit user reported that a long-standing bug in the ICM calculator has been fixed. Specific case: AKs hand, 10BB vs 12BB, payout structure 50/30/20. Calculations showed a fold $EV difference of -2.45, meaning folding was a serious mistake. The bug may have previously misled player decisions and has now been corrected.
Recently, a Reddit user posted in the r/onlinepoker subreddit pointing out that a commonly used ICM calculator had a long-standing bug that has now been fixed. The user provided a specific example to demonstrate the corrected result.
Case Details: AKs at the Bubble Edge in ICM Decision
- Hand: AKs (Suited Ace-K)
- Stacks: 10 BB (Big Blind) vs Opponent 12 BB
- Payout Structure: 50%/30%/20% (1st 50%, 2nd 30%, 3rd 20%)
- Scenario: Assume on the bubble edge, facing an opponent's all-in, should you call?
Pre-Fix Error and Post-Fix Correct Result
According to the user's screenshot (link omitted), the corrected calculation shows: if you fold, the $EV difference is -2.45. This means folding results in a loss of 2.45 buy-in units of EV (units depend on prize pool size) in expected tournament value. In other words, calling has higher EV than folding, so calling is the correct decision.
Before the fix, the calculator may have given the opposite or incorrect value, leading players to believe folding was better. This error is especially dangerous in ICM decisions because ICM (Independent Chip Model) is used to calculate the expected prize value of different actions in tournaments, and even small inaccuracies can change the decision direction.
Why ICM Calculations Matter?
In poker tournaments, the marginal value of chips is not linear – as you approach the money or the final table, each chip's value changes due to the payout ladder. The ICM model converts chip counts into "$EV" (expected prize value), helping players evaluate the long-term profitability of calling, folding, or raising.
For this example:
- 10BB vs 12BB: stacks are close, but AKs is a very strong hand.
- Under ICM pressure (50/30/20 structure), folding might seem safe, but the calculated -2.45 $EV indicates that the cost of folding is much higher than the risk of calling. Typically, if the $EV difference of folding is negative, it means the EV of calling is positive, so you should call.
Community Reaction and Takeaways
The post received significant attention, with many players thanking the poster for the feedback and reminding others to update their calculator versions regularly. This also serves as a reminder to all poker enthusiasts: be cautious when relying on tools – even mature calculators can have hidden bugs. For high-stakes or critical final table decisions, it is advisable to cross-check multiple tools or use your own ICM knowledge to make judgments.
The calculator has now been fixed, and users can use it confidently. However, at the table, the final decision should still incorporate opponent tendencies, your own range, and live dynamics.
FAQ
- $EV difference represents the difference in expected prize value of one action e.g., fold relative to another action e.g., call. If the $EV difference for folding is negative, it means folding loses that much $EV compared to calling, i.e., calling is the better choice.