Expected Value Calculator
Determine a wager's +EV from the price and your estimated true probability.
How to Use This Calculator
- Select your odds format (Decimal, Fractional, or American)
- Input the bookmaker’s odds for the selection
- Input your estimated true win probability (expressed as a percentage)
- Input your intended stake amount
- The tool returns the expected value, edge percentage, and whether the bet is +EV
Formula
Expected Value = (Win Probability × Profit) - (Loss Probability × Stake)
EV per unit = (p × (Decimal Odds - 1)) - (1 - p)
Edge % = EV per unit × 100
Where p = your estimated win probability (as a decimal)
Frequently Asked Questions
What is expected value in the context of betting?
Expected value (EV) is the average win or loss you can expect per bet across the long run. Positive EV (+EV) signals a bet that is profitable over time, whereas negative EV (-EV) signals one that loses money over time.
What is the meaning of +EV?
A +EV (positive expected value) bet indicates you hold an edge over the bookmaker. Place +EV bets consistently and you’ll come out ahead over the long run, even though any single bet can still lose.
What's the method for estimating the true probability?
You can derive true probability from your own research, statistical models, or by cross-referencing odds across several bookmakers. The decisive factor is arriving at a more accurate probability estimate than the bookmaker’s.
Is it possible to lose on +EV bets?
Yes — individual +EV bets can lose. Expected value is a long-run concept. Across hundreds or thousands of bets, positive EV converts to profit, but short-term variance makes individual losses entirely normal.