Calculate Expected Value
Whether a bet is +EV from the price and your true-probability estimate.
How to Use This Calculator
- Pick your odds format (Decimal, Fractional, or American)
- Enter the bookmaker’s odds for the selection
- Enter your estimated true probability of winning, as a percentage
- Set the stake you plan to put down
- See the expected value, edge percentage, and whether the bet grades out as +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 you can expect to win or lose per bet over the long haul. Positive EV (+EV) means the bet pays off over time, while negative EV (-EV) means you bleed money the longer you play.
What does +EV actually mean?
A +EV (positive expected value) bet means you hold an edge over the bookmaker. Keep stacking +EV bets and you’ll come out ahead long term — even though any single bet can still go sideways.
How do I estimate the true probability?
Lean on your own research, statistical models, or odds comparisons across several bookmakers to land on a true probability. The whole game is being more accurate than the bookmaker.
Can a +EV bet still lose money?
Absolutely — any individual +EV bet can lose. Expected value plays out over the long run. Across hundreds or thousands of bets, positive EV turns into profit, but short-term variance makes the odd loss completely normal.