Glossary · Games and odds
Expected value: definition and example
Average result of a bet if it were repeated a very large number of times; it is negative for almost every casino game.
Definition
Expected value is calculated by multiplying each possible outcome by its probability, then adding everything up. An expected value of −2.70% means that a €100 bet loses €2.70 on average. It is also used to estimate the average cost of a bonus.
Example
A €10 bet on red at European roulette wins €10 with 18 chances out of 37 and loses €10 with 19 chances out of 37: its expected value is −€0.27.
What to check
A negative expected value does not mean you lose every time, only that you lose on average over the long run.
