Effective Stack

The smallest of the stacks involved — the only one that matters

Definition

The effective stack is the smallest of the stacks involved in a hand: it's the maximum each player can win or lose. If you have 250bb and your opponent 30bb, you're playing a 30bb hand — your extra 220bb don't exist for this hand. The effective stack conditions the entire strategy. Deep (150bb+), implied odds explode: small pairs and suited connectors gain value, but dominated hands become dangerous (you lose big pots on kicker battles). Standard (100bb), it's the terrain of classic ranges. Short (under 40bb), speculative draws lose their profitability (not enough left to win), the game simplifies around pairs and aces, and below ~15bb you switch to push/fold. It's one of the first things to check before any preflop decision: the same hand, in the same position, against the same opponent, plays differently at 25bb and at 100bb effective. Playing your "100bb range" against a short stack is a classic leak — set-mining with 22 against an open is only profitable if the effective stack offers ~15 times the price of the call.