What Is Expected Value (EV) in Sports Betting?
Written by the DawBets analytics team · Updated April 2026 · 7 min read
Expected value is the mathematical edge that separates long-term profitable bettors from everyone else. Here's how it works, why it matters, and how to find +EV bets.
Quick answer
Expected value (EV) measures the average profit or loss you'd expect if you placed the same bet thousands of times. A positive EV bet means the sportsbook's odds are better than the true probability — you have a mathematical edge. Over hundreds of bets, +EV bettors profit while -EV bettors lose.
The coin flip analogy
Imagine someone offers you a bet: flip a fair coin, and if it lands heads, you win $120. Tails, you lose $100. Would you take it?
Most people instinctively feel this is a good deal, and the math confirms it. On each flip, you have a 50% chance of winning $120 and a 50% chance of losing $100. Your expected value per flip is:
That +$10 doesn't mean you'll win $10 every flip. You'll win some and lose some. But over hundreds of flips, your average profit converges toward $10 per flip. That's expected value: the long-run average outcome of a repeatable bet.
The EV formula
For sports betting, expected value measures whether a bet is priced in your favor. The formula:
When EV is positive (+EV), the bet has a mathematical edge in your favor. When it's negative (-EV), the sportsbook has the edge. Most bets at most sportsbooks are -EV — that's how sportsbooks make money.
The key challenge is determining the true win probability. Sportsbooks embed a margin (called vig or juice) into their odds, making every bet appear slightly worse than fair. DawBets uses a process called devigging to strip out the margin and estimate fair probabilities.
A real-world betting example
Let's say DraftKings offers the Buffalo Bills moneyline at +150 (bet $100 to win $150). After devigging the market across multiple sportsbooks, DawBets estimates the Bills' true win probability at 42%.
Fair probability (devigged) = 42.0%
EV = (0.42 × $150) - (0.58 × $100)
EV = $63 - $58 = +$5.00 (+5.0%)
A +5% EV means that for every $100 wagered on bets like this, you'd expect to profit $5 on average over time. This specific bet might win or lose — variance is real and must be respected — but the math is in your favor.
Why most bettors lose: the vig
Every sportsbook builds a margin into their odds. A fair coin-flip bet should be priced at +100 on both sides, but a sportsbook prices it at -110/-110. That ~4.5% margin is the vig (short for vigorish), and it's how sportsbooks guarantee profit regardless of outcomes.
Recreational bettors who pick games based on gut feel are betting into this margin on every wager. Over time, the vig erodes their bankroll at a steady, predictable rate. This isn't bad luck — it's math.
+EV betting flips this dynamic. By finding bets where the sportsbook's price implies a lower probability than the true probability, you're exploiting pricing inefficiencies. Different sportsbooks price the same event differently, and those discrepancies create edges. Line shopping — comparing prices across books — is how you find them.
How DawBets finds +EV edges
DawBets monitors odds from 20+ sportsbooks in real time, applies devigging algorithms to estimate fair probabilities, and calculates the expected value of every available bet.
Each bet receives a badge rating based on its EV:
- Must Bet — 7%+ EV. Strongest edges
- Strong Bet — 3.5%+ EV. High confidence
- Great Bet — Above 0% EV. Positive expectation
- Fan Bet — -2% to 0% EV. Near-fair
- Caution — Below -2% EV. Sportsbook has a clear edge
DawBets tracks real-time odds across 20+ sportsbooks to find positive expected value edges.
Frequently asked questions
Can you guarantee profit with +EV betting?
No. Expected value describes long-term averages, not individual outcomes. A +5% EV bet still loses frequently in small samples. Variance is real — the edge only materializes over a large number of bets.
How many bets before EV "kicks in"?
There's no magic number. The law of large numbers means your actual results converge toward expected value as sample size grows. Most serious EV bettors track hundreds or thousands of bets before drawing conclusions.
What does "devigging" mean?
Devigging (or de-vigging) is the process of removing the sportsbook's built-in margin from their odds to estimate the true fair probability. DawBets uses multiple devig methods (additive, multiplicative, power) and compares across 20+ books.
Is EV betting the same as arbitrage?
No. Arbitrage guarantees profit on a single event by betting both sides at different books. EV betting identifies bets with a mathematical edge on one side — each individual bet can win or lose, but the edge is profitable over time.