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ICM basics: why bubble folds are correct

October 28, 2026 · 7 min read · ICM

Chips aren't dollars

In a cash game, doubling your stack doubles your money. In a tournament it doesn't. Prizes are paid by finishing position, and you can't cash out chips. The Independent Chip Model (ICM) turns a set of stacks and a payout table into each player's dollar equity. The trainer uses the standard Malmuth-Harville version: your chance of finishing 1st is your share of the chips, and the lower places follow the same rule among the players left.

The worked example

Five players left, four get paid: $3,000 / $1,900 / $1,300 / $950. Stacks in big blinds:

Look at the chip leader. He has 3× your chips but only about 1.6× your equity. Chips at the top of the stack are worth less, which is why big stacks can afford to put pressure on everyone else.

The chip leader shoves the button with a wide range (about 43% of hands). The small blind folds. You're in the big blind with 20 BB.

Chip EV vs ICM

After posting, folding leaves you with 18 BB. Calling risks 19 more to win a 39.5 BB pot.

• Chip EV: you need (18 − 0) / (39.5 − 0) ≈ 45.6% equity to call.
• ICM: folding keeps $1,346 of equity, winning the all-in is worth $1,883, and losing busts you on the bubble for $0. Required equity = (1,346 − 0) / (1,883 − 0) ≈ 71.5%.

The bubble factor (what losing a chip costs compared with what winning one gains) is about 2.9 for you against the chip leader. Against the 9 BB short stack it's only about 1.25. Who covers whom matters as much as the cards.

Which hands can call?

Folding jacks feels terrible, and it's correct here. A 9 BB stack is about to blind out, and every time he busts first you get paid at least $950. Calling puts that in danger for a small gain in chips.

Three bubble rules of thumb

1. Medium stacks tighten calls against players who cover them. This example is the extreme case.
2. Big stacks put pressure on medium stacks. Their shoves get through because the mediums can't call.
3. Short stacks keep shoving. Their fold equity comes from the ICM pressure on the medium stacks.

Limits of the model

Malmuth-Harville ICM ignores skill, future hands and blind pressure, so it tends to overstate how tight you should be with a big skill edge or very deep stacks. It's still the standard starting point. The trainer's ICM mode shows payouts, your $-equity and the bubble factor on every bubble, pay-jump and final-table spot, so the reasoning stays visible.

Training content, not financial advice. Numbers come from the Play Perfect Poker trainer's own models (labelled reference, approximate or heuristic) and simplify real play. No real-money gambling is offered on this site.