Expected value (EV) is the average outcome of a bet over many repetitions. A positive EV bet is one you should make. A negative EV bet is one you should avoid. Here's how to calculate it for any sports bet.
The Expected Value Formula
EV = (Probability of Win × Profit if Win) - (Probability of Loss × Stake Lost)
Example: You bet $100 on a team at +150. You estimate the true probability of winning is 45%.
- Profit if win: $150
- Loss if lose: $100
- EV = (0.45 × $150) - (0.55 × $100)
- EV = $67.50 - $55.00 = +$12.50
A +$12.50 EV means you expect to profit $12.50 per $100 wagered over many repetitions.
Negative EV Example
Same bet, but you actually have only a 38% chance of winning (the market's estimate is correct and you have no edge):
- EV = (0.38 × $150) - (0.62 × $100)
- EV = $57 - $62 = -$5.00
Negative EV = expected loss over time.
How to Estimate Win Probability
The challenge: you don't know true probability exactly. Methods:
- Use no-vig fair odds as the baseline (market's best estimate)
- Compare your research against the no-vig price
- If you have a specific edge (injury news, weather data, matchup analysis), adjust accordingly
EV-Based Decision Making
The goal: only bet when EV is positive. The discipline: decline bets that look appealing but where the true probability doesn't support it.
Tools like Oddible calculate EV automatically for you — grading each bet Great/Good/Fair/Bad based on the no-vig fair price at the time you're considering the bet.
[See EV automatically on any bet with Oddible →]
