What is Expected Value (EV)?
Expected value (EV) is the mathematical expectation of profit or loss on a bet over time. It represents how much you can expect to win (or lose) on average per dollar wagered.
A positive EV (+EV) bet means you have an edge over the sportsbook. A negative EV (-EV) bet means the house has the edge. Professional bettors focus exclusively on +EV opportunities.
Key Insight: You can lose individual +EV bets, but over hundreds or thousands of bets, +EV betting is mathematically guaranteed to be profitable.
The Expected Value Formula
The basic EV formula for a single bet is:
EV = (Win Probability × Profit if Win) - (Loss Probability × Stake)
Or simplified:
EV = (P × W) - ((1 - P) × S)
Example Calculation
You estimate a team has a 55% chance to win. The odds are +120 ($100 stake pays $120 profit).
- Win Probability (P) = 0.55
- Profit if Win (W) = $120
- Loss Probability = 0.45
- Stake (S) = $100
EV = (0.55 × $120) - (0.45 × $100) = $66 - $45 = +$21
This is a +21% EV bet - excellent value!
How to Find +EV Bets
Common +EV Opportunities
Odds Boosts
Sportsbook promotions often offer +EV. Use our boost calculator to evaluate.
Player Props
Less efficient markets with more mispriced lines. Our prop EV calculator helps analyze.
Live Betting
Fast-moving lines create temporary +EV windows for quick bettors.
Opening Lines
Early lines are often softer before sharp money moves them.
Frequently Asked Questions
What is expected value (EV) in sports betting?
Expected value is the average profit or loss per bet over time. +EV bets are profitable long-term, while -EV bets lose money. EV = (Probability × Win) - ((1 - Probability) × Stake).
How do you find +EV bets?
Develop your own probability estimates through research, compare them to the implied probability from odds, and bet when your estimate exceeds the book's implied probability.
What is a good expected value percentage?
Professional bettors target 2-5% EV. Even 1% edge is valuable at high volume. Above 5% is excellent but rare in efficient markets.