Expected Value Helper
Find out if a bet is +EV from the odds and your own estimate of the true chance.
How to Use This Calculator
- Pick your odds format (Decimal, Fractional, or American)
- Enter the bookmaker’s odds for your selection
- Add your estimated true probability of winning (as a percentage)
- Enter the stake you plan to put down
- See the expected value, your 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 when betting?
Expected value (EV) is the average amount you can expect to win or lose on a bet over the long run. A positive EV (+EV) means the bet pays off over time, while a negative EV (-EV) means you’ll lose money in the long run.
What does +EV actually mean?
A +EV (positive expected value) bet means you hold an edge over the bookmaker. Keep placing +EV bets and you’ll come out ahead over the long run, even though any single bet can still lose.
How do I work out the true probability?
You can estimate true probability through your own research, statistical models, or by lining up odds from several bookmakers. The whole trick is having a sharper probability estimate than the bookmaker does.
Is it possible to lose on +EV bets?
Yes, any individual +EV bet can lose. Expected value is a long-term idea. Across hundreds or thousands of bets, positive EV turns into profit, but short-term swings mean the odd loss along the way is completely normal.