What is Expected Value in Sports Betting?
What is Expected Value?
Expected value (EV) is a mathematical concept that tells you the average outcome of a bet if you were to make that exact same wager an infinite number of times. A positive EV (+EV) means you stand to profit over the long run. A negative EV (-EV) means the book has the edge.
Every casino game, lottery ticket, and sportsbook wager has an expected value. The house advantage in roulette, the edge on a slot machine, the vig in a -110 football line — all are forms of negative EV built in to ensure the operator profits.
Sharp bettors operate in the opposite direction: they hunt for positive expected value — situations where the sportsbook has mispriced a market and is offering better-than-fair odds.
The EV Formula
Expected value has two equivalent forms:
Or in terms of decimal odds, which sharp bettors prefer:
A result above 0% means you have a positive edge on this bet. A result below 0% means the book has priced this market in their favor and you should pass.
Real-World Example
Imagine a sportsbook is offering +150 on a coin flip. The true probability of heads is 50%. Let's calculate the EV on a $100 bet:
| Outcome | Probability | Net Result | EV Contribution |
|---|---|---|---|
| Win (heads) | 50% | +$150 | +$75 |
| Loss (tails) | 50% | −$100 | −$50 |
| Total EV | +$25 |
The EV is +$25 per $100 staked, or +25% EV. In decimal terms: (0.50 × 2.50 − 1) × 100 = +25%. If you placed this bet a thousand times, you'd expect to profit around $25,000. Individual results will vary, but the edge compounds over time.
Tip: You don't need to know the exact true probability. Using a sharp market maker (like Pinnacle) as your reference removes the vig and gives you a reliable fair probability for any outcome.
Why Sharp Bettors Obsess Over EV
Most recreational bettors focus on picking winners. Sharp bettors focus on finding edges — situations where the offered odds exceed what the true probability justifies. You can lose more bets than you win and still be profitable, as long as your average EV per bet is positive.
This is why closing line value (CLV) matters more than win rate. If you consistently get better odds than where the line closes at game time, you're demonstrating that you're betting into mispriced markets — the definition of a sharp bettor.
How to Find +EV Bets
The workflow used by professional bettors:
- Use a sharp market (Pinnacle, Circa, or an exchange) as your reference price.
- Remove the vig to derive the true no-vig fair probability.
- Compare every other sportsbook's price against the fair line.
- Bet wherever the offered odds beat the fair price.
Done manually, this process takes minutes per line and you'll often miss opportunities before they close. EVstrike automates the entire pipeline — scanning 20+ books, calculating no-vig EV against Pinnacle, and surfacing opportunities in real-time.
Try the free EV Calculator
Calculate EV from any American odds instantly — no login required.