EV adds up every possible outcome weighted by its probability.
Example - Dice. A bet that pays 2× with a 49.5% chance to win:
- Win: 0.495 × 2 = 0.99 returned per $1
- EV = 0.99 − 1 = −$0.01 per $1 bet, i.e. a 1% house edge.
EV is additive. 1,000 such bets of $1 have an EV of −$10, regardless of order, bet sizes in between, or any system you use. That's why no strategy can turn negative-EV bets into a positive-EV session.
What EV doesn't tell you: how wide the swings are. Two games with the same EV can feel completely different - that's variance.
In ProvablyHero tools
The calculator shows EV per bet and expected loss per session.