Expected Value (+EV)
The only math that actually matters in sports trading.
The Core Concept
Expected Value (EV) measures what a bettor can expect to win or lose if they were to place the same bet on the same odds repeatedly. According to a 2022 paper by the Journal of Quantitative Analysis in Sports, fewer than 2% of bettors maintain a positive expected value over a sample size exceeding 5,000 wagers.
The Formula
(Probability of Winning × Amount Won) - (Probability of Losing × Stake) = EV
Worked Example
Suppose Pinnacle prices the Kansas City Chiefs at -110 (1.91). You build a model that predicts KC has a 55% chance of covering the spread.
| Metric | Value |
|---|---|
| True Win Probability | 55.0% (0.55) |
| True Loss Probability | 45.0% (0.45) |
| Stake | $100 |
| Potential Profit | $90.91 |
Calculation: (0.55 * $90.91) - (0.45 * $100) = $50.00 - $45.00 = +$5.00 (+5% EV).
Common Mistakes
- Confusing EV with guarantees: A +5% EV bet still loses 45% of the time. Variance dictates that you will experience drawdowns.
- Using the wrong 'True' probability: If your model is flawed, your EV calculation is garbage (GIGO). Always compare your model against the closing line of sharp books.
FAQ
- Is a 2% EV good?
- Yes. Over a large sample (10,000+ bets), a 2% yield on turnover is a highly profitable, professional-level return.