How much is the biggest stack worth in ICM with 4 players left?

Seat 1 holds 15,000 chips, 37.5% of the chips in play, and is worth 32.9% of the prize pool when 3 places pay 50/30/20 percent. That is -4.57 points against its chip share.

What equity does the smallest stack need to call the biggest stack's all-in?

65.3%. In chips alone the call breaks even at 50%, but the bubble factor of 1.88 raises the requirement because losing costs the smallest stack 17.07% of the prize pool.

Why is ICM equity different from chip share?

Because the prize pool is paid by place, not by chips. Doubling a stack does not double its payout, so each extra chip is worth less than the one before it. Here the biggest stack is worth 32.9% of the prize pool for 37.5% of the chips.

ICM: Two big stacks, 4 Players, 3 Paid

In ICM, 15,000 chips out of 4 players is 37.5% of the chips and 32.9% of the prize money when 3 places pay 50/30/20 percent. The 5,000-chip stack holds 12.5% of the chips and is worth 17.1%.

How much is each stack worth with 4 players left?

Here the stacks follow the two big stacks pattern, where two players hold 15,000 chips each and the rest hold 5,000 each. Together they hold 40,000 chips, and three places paid, 50, 30 and 20 percent. Read each seat's prize equity against its chip share in the table.

Chips and prize equity with 4 players left, payouts 50/30/20 percent
Seat	Chips	Share of chips	ICM equity	ICM minus chips
Seat 1	15,000	37.50%	32.93%	-4.57 points
Seat 2	15,000	37.50%	32.93%	-4.57 points
Seat 3	5,000	12.50%	17.07%	+4.57 points
Seat 4	5,000	12.50%	17.07%	+4.57 points

Share of the chips against share of the prize pool

Seat 1Chips 37.5%Prize 32.9%
Seat 2Chips 37.5%Prize 32.9%
Seat 3Chips 12.5%Prize 17.1%
Seat 4Chips 12.5%Prize 17.1%

Prize money flattens the stacks. Seat 2 gives up 4.57 points of equity compared with its share of the chips, and Seat 3 gains 4.57 points.

How often does each seat finish in the money?

ICM gets each equity from the chance of finishing in every place. The Seat 4 stack (5,000 chips) is paid 58.2% of the time, and the Seat 1 stack (15,000 chips) is paid 91.8% of the time.

Chance of finishing in each place
Seat	First	Second	Third	Fourth	Paid
Seat 1	37.50%	33.21%	21.07%	8.21%	91.79%
Seat 2	37.50%	33.21%	21.07%	8.21%	91.79%
Seat 3	12.50%	16.79%	28.93%	41.79%	58.21%
Seat 4	12.50%	16.79%	28.93%	41.79%	58.21%

Where each seat's prize equity comes from, in points of the prize pool
Seat	From first	From second	From third	Total
Seat 1	18.75	9.96	4.21	32.93%
Seat 2	18.75	9.96	4.21	32.93%
Seat 3	6.25	5.04	5.79	17.07%
Seat 4	6.25	5.04	5.79	17.07%

What is the bubble factor for each seat with 4 players left?

The bubble factor is the prize equity a player loses by losing an all-in divided by the equity gained by winning it. The highest figure here is 2.81, for Seat 1 calling Seat 2, and the lowest is 1.17, for Seat 1 calling Seat 3.

Bubble factor when the row seat calls an all-in from the column seat
Seat	vs Seat 1	vs Seat 2	vs Seat 3	vs Seat 4
Seat 1	none	2.81	1.17	1.17
Seat 2	2.81	none	1.17	1.17
Seat 3	1.88	1.88	none	1.27
Seat 4	1.88	1.88	1.27	none

How much equity does a call need?

When the smallest stack (Seat 4) calls an all-in from the biggest (Seat 1), the bubble factor is 1.88. A call that needs 50% in chips needs 65.3% once prize money counts, which is 15.3 points more. The same all-in the other way, with the biggest stack calling the smallest, has a bubble factor of 1.17 and needs 54.0%, 4.0 points over the chip figure. The smaller stack is the one that pays the larger ICM premium, because losing the all-in costs it 17.07% of the prize pool and winning adds 9.07%.

Break-even equity for two all-in calls, risking and winning the same chips
Call	All-in (chips)	Bubble factor	Chip break-even	ICM break-even	Equity now	Equity if win	Equity if lose
Smallest stack calls biggest	5,000	1.8819	50.0%	65.3%	17.07%	26.14%	0.00%
Biggest stack calls smallest	5,000	1.1728	50.0%	54.0%	32.93%	38.71%	26.14%

Where can I compare other stack patterns?

Open a sibling to see how the same payouts value a different split of the chips. For your own stacks and payouts, use the ICM calculator.

How was this ICM table computed?

Each player finishes first with a chance equal to their share of the chips, and every later place is drawn the same way from the players left. Prize equity is the payout of each place times the chance of finishing there. The bubble factor divides the equity lost by losing an all-in by the equity gained by winning it, with the other stacks unchanged, and a player who reaches 0 chips takes the lowest place.

Source: Malmuth-Harville ICM, computed by GeorgeLiPoker's own library. The model follows D. A. Harville, 'Assigning Probabilities to the Outcomes of Multi-Entry Competitions', Journal of the American Statistical Association, 1973.

Questions

How much is the biggest stack worth in ICM with 4 players left?: Seat 1 holds 15,000 chips, 37.5% of the chips in play, and is worth 32.9% of the prize pool when 3 places pay 50/30/20 percent. That is -4.57 points against its chip share.
What equity does the smallest stack need to call the biggest stack's all-in?: 65.3%. In chips alone the call breaks even at 50%, but the bubble factor of 1.88 raises the requirement because losing costs the smallest stack 17.07% of the prize pool.
Why is ICM equity different from chip share?: Because the prize pool is paid by place, not by chips. Doubling a stack does not double its payout, so each extra chip is worth less than the one before it. Here the biggest stack is worth 32.9% of the prize pool for 37.5% of the chips.