Expected Value of a Game Calculator
Find the long-run average outcome of a bet or game — enter the win amount, loss amount and win probability to see if it pays.
How it works
EV = P(win) × gain − P(lose) × loss · Edge% = EV ÷ stake × 100
Expected value is the probability-weighted average of every outcome — what you would win or lose per play if you repeated the game forever. A positive EV means the game favors you in the long run; a negative EV means it drains money over time even if individual plays sometimes win. It says nothing about a single play, only the long-run average, which is why swings still happen.
Worked example
A game pays $100 on a 45% win and costs $100 on a 55% loss: EV = 0.45 × 100 − 0.55 × 100 = 45 − 55 = −$10 per play. Over 100 plays you would expect to lose about $1,000, a −10% edge on a $100 stake.
Sources: Expected value — Wikipedia
Frequently asked questions
What does a negative expected value mean?
It means the game loses money on average over many plays. You can still win a single round, but repeated play trends toward the negative EV per play.
Does positive EV guarantee I win?
No. EV is a long-run average, not a promise for any one play. A positive-EV bet can lose many times in a row; the edge only reliably shows over a large number of plays.
How should I enter the loss amount?
Enter the loss as a positive number — the calculator subtracts it. If you lose your $100 stake, enter 100 as the loss.
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This calculator is for educational purposes. Double-check important results before acting on them.