Expected Value Tool
Check whether a bet is +EV from the odds and your estimated true probability.
How to Use This Calculator
- Pick your odds format (Decimal, Fractional, or American)
- Input the bookmaker’s odds for the selection
- Input your estimated true win probability (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 betting?
Expected value (EV) is the average win or loss per bet over the long run. Positive EV (+EV) means the bet pays off long-term; negative EV (-EV) means you lose money over time.
What does +EV mean?
A +EV (positive expected value) bet means you hold an edge over the bookmaker. Place +EV bets consistently and you profit long-term, even though single bets can still lose.
How is true probability estimated?
Estimate true probability from your own research, statistical models, or by comparing odds across several bookmakers. The point is to land on a more accurate probability than the bookmaker’s.
Can a +EV bet still lose?
Yes, individual +EV bets can lose. Expected value is a long-term measure. Across hundreds or thousands of bets, positive EV turns a profit, but short-term variance makes individual losses normal.