What Is Expected Value (+EV) in Sports Betting?
A friend offers you +110 on a fair coin flip. You should take that bet every time. You will lose plenty of flips, but over a hundred of them you expect to be up about $500 on $100 flips. Now flip it around: a sportsbook offers you -110 on the same coin. That bet loses money in the long run no matter how many times you win it. The difference between those two bets is expected value, and it is the most important idea in sports betting.
What does +EV mean in sports betting?
"+EV" (positive expected value) means the odds you are getting pay more than the true chance of winning deserves. "-EV" means they pay less. Every sportsbook price has a built-in vig, so most bets at most prices are slightly -EV. Winning bettors are the ones who find the exceptions.
The key word is "long run." A single +EV bet can lose, and a single -EV bet can win. EV describes what happens on average across a large number of similar bets, which is why sharp bettors care about making good bets more than about any one result.
The expected value formula
You need two things: the odds and your honest estimate of the win probability.
| Odds | True win chance | Profit if it wins | EV per $100 |
|---|---|---|---|
| -110 | 50% | $90.91 | −$4.55 |
| -110 | 55% | $90.91 | +$5.00 |
| +200 | 30% | $200 | −$10.00 |
| +200 | 36% | $200 | +$8.00 |
| -200 | 65% | $50 | −$2.50 |
| -200 | 70% | $50 | +$5.00 |
| +400 | 22% | $400 | +$10.00 |
Break-even odds: the number hidden in every price
Every price implies a break-even win rate. If your true chance of winning is higher than that number, the bet is +EV. If it is lower, the bet is -EV. This is the fastest way to size up any line. Our guide on how to read betting odds shows the conversion formula.
| Odds | Break-even win rate | Odds | Break-even win rate |
|---|---|---|---|
| -300 | 75.0% | +100 | 50.0% |
| -200 | 66.7% | +120 | 45.5% |
| -150 | 60.0% | +150 | 40.0% |
| -120 | 54.5% | +200 | 33.3% |
| -110 | 52.4% | +300 | 25.0% |
| -105 | 51.2% | +400 | 20.0% |
Where does your win probability come from?
Anyone can do the EV formula. The edge is in the win probability you plug into it. Bettors usually get there one of three ways:
Why most parlays are -EV
Each leg of a standard parlay carries its own vig, and the parlay multiplies them together. If every leg is a true 50-50 game at -110, the math gets worse with each leg you add.
That does not mean a parlay can never be +EV. If each leg is +EV on its own, the parlay compounds your edge instead of the book's. Odds boosts can also flip the math: a 30% profit boost on a true coin flip at -110 turns a −$4.55 bet into about +$9.09 per $100.
Practical ways bettors find +EV
- Line shopping. The same bet at -105 instead of -110 lowers your break-even from 52.4% to 51.2%. Compare prices on the live odds page.
- Stale lines. When news breaks, some books move slower than others. The first minutes after an injury report are where a lot of value lives.
- Promotions and boosts. Profit boosts, odds boosts and bonus bets can create +EV spots. Read the terms.
- Smaller markets. Player props and lower-profile games get less attention from oddsmakers, so prices can be further off.
- Disciplined sizing. A +EV bettor who bets too big can still go broke. Pair value with bankroll management.
Expected value questions
What does +EV mean in betting?
How do you calculate EV on a bet?
Can a +EV bet lose?
Are parlays ever +EV?
What is the best way to find +EV bets?
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