Definition
Expected Value (EV) is the cornerstone mathematical concept in poker decision-making. It represents the average outcome of a decision if it were repeated an infinite number of times. A +EV decision is one that makes money over time; a -EV decision loses money over time.
EV is calculated by multiplying each possible outcome by its probability and summing the results. For example, if calling a bet will win the pot 40% of the time and lose your call 60% of the time, you multiply each scenario by its probability and add them together to find the EV of calling.
Maximizing EV — making the highest-EV decision in every situation — is the goal of professional poker play. The concept extends beyond individual hand decisions to bankroll management, game selection, and even life decisions. "EV" has entered the vocabulary of the broader rationalist community as a framework for optimal decision-making.
Example
If you bet $100 as a bluff and your opponent folds 60% of the time (winning $200 pot) and calls 40% (losing $100): EV = (0.60 × $200) + (0.40 × -$100) = $120 - $40 = +$80. The bluff is +EV.