rules
Effective stack
The smaller of the two stacks in a hand — the most that can be won or lost between those players. All strategy calculations use the effective stack, not your own.
Example. A 15 bb short stack shoves; the 100 bb chip leader calls, risking only 15 bb — the effective stack.
If you have 200 big blinds and your opponent has 25, you are playing a 25-big-blind hand against them, however deep you feel. In multiway pots the effective stack differs for each opponent, which is one reason multiway spots are so complex. Tournament players constantly check effective stacks before deciding whether a shove or a raise is the right tool.