Definition
Expected Value (EV) is the mathematical concept at the heart of profitable betting. It represents the average profit or loss you would experience per bet if you repeated the same wager an infinite number of times. A positive EV (+EV) bet is profitable in the long run; a negative EV (-EV) bet is a losing proposition over time.
How It Works
Formula: EV = (Probability of Winning x Net Profit) - (Probability of Losing x Stake)
Alternatively: EV = (Odds x Estimated Probability) - 1, expressed as a percentage of the stake. If EV > 0, the bet has positive expected value. The challenge lies in accurately estimating the true probability, which is what separates skilled bettors from recreational ones.
Example
Bet: odds of 2.50, your estimated win probability is 45%
- EV = (0.45 x $150) - (0.55 x $100) = $67.50 - $55 = +$12.50 per $100 bet
- As a percentage: (2.50 x 0.45) - 1 = +12.5%
Over 100 such bets at $100 each, you would expect to profit approximately $1,250.
Why It Matters
Expected value is the single most important concept in betting. Every profitable bettor thinks in terms of EV rather than individual wins and losses. A bet can lose and still have been the right bet to place if it had positive EV. Conversely, a winning bet at negative EV was a bad bet -- you just got lucky. Training yourself to evaluate bets by their expected value rather than their outcome is the mental shift that separates professionals from amateurs.
Use our EV calculator to quickly determine whether a bet has positive expected value based on your estimated probability and the offered odds.