Bubble Factor

Also known as: BF, ICM bubble factor

The ratio of $EV lost when you lose a chip to $EV gained when you win one in a given all-in — a direct measure of ICM pressure.

Bubble factor quantifies how much more it hurts to lose than it helps to win in a specific confrontation. It is the ratio:

\[ \text{BF} = \dfrac{\$\text{EV lost per chip if you bust}}{\$\text{EV gained per chip if you double}} \]

A bubble factor of 1.0 is a pure chip-EV spot (early MTT, deep stacks) — chips won and lost are worth the same. A bubble factor of 1.5 means losing hurts 50% more than winning helps; on a satellite money bubble it can climb to 3+ between two covering stacks. The higher it is, the tighter you must continue.

Bubble factor and risk premium are two views of the same ICM pressure: bubble factor is the loss/gain ratio, risk premium converts that into the extra equity your calling hand needs. Note it is pairwise — it differs for each opponent depending on who covers whom.

Example

On the bubble, a covered medium stack faces a chip leader's shove. Solvers give a bubble factor around 1.7 for that pairing. Required equity to call rises from 50% (BF = 1) to roughly 1.7 / (1 + 1.7) ≈ 63%, so any hand flipping at 50-55% is now a clear fold against the cover.