EV Calculator
Compare your rec book's odds against de-vigged sharp lines to see if a bet has positive expected value.
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What Is Expected Value (EV)?
Expected value tells you whether a bet is profitable in the long run. If you placed the same bet thousands of times, would you come out ahead or behind? A +EV bet means the odds you're getting are better than the true probability — you have an edge. A -EV bet means the book has the edge over you.
How This Calculator Works
The key insight is that sharp sportsbooks (like Pinnacle) have the most efficient odds in the market. Their lines are the closest thing to “true odds” that exists. But even Pinnacle has a small profit margin built into their lines. This calculator:
- Takes the sharp book's odds for both sides of a market
- Strips out the vig (profit margin) to find the true fair probability
- Compares that fair probability against what your rec book is offering
- Shows you the EV — whether you have an edge and how big it is
What Makes a Sharp Book?
Sharp sportsbooks like Pinnacle, Circa, and Bookmaker welcome high-volume and professional bettors. This means their odds are shaped by the sharpest money in the market. Their lines tend to be the most accurate reflection of true probabilities. That's why we use them as the baseline for finding fair odds.
How to Use It
- Enter both sides of the sharp book's line (e.g., Pinnacle has Chiefs -160 / 49ers +140)
- Click which outcome you want to bet on (e.g., “49ers”)
- Enter the odds your rec book is offering for that outcome (e.g., DraftKings has 49ers at +155)
- The calculator instantly shows the EV — in this case, around +7% EV
Worked Example
Pinnacle has Celtics -180 / Knicks +155. Using the Power de-vig method, the true fair probability is Celtics 63.2% / Knicks 36.8%. The fair Knicks line is +172 in American odds. But FanDuel is offering Knicks at +185. That's better than fair — you're getting paid more than the true odds imply. The EV calculation: (0.368 × 1.85) - (0.632 × 1) = 0.681 - 0.632 = +4.9% EV. For every $100 you bet on this spot, you expect to profit $4.90 in the long run.
When to Use This vs. Other Tools
The EV Calculator is your go-to when you want to know if a specific bet is worth taking. Use the De-Vig Calculator when you just want to find the true fair odds for a market without evaluating a specific bet. Use the Kelly Criterion Calculator after you've confirmed a bet is +EV and want to know how much to wager. The typical workflow: de-vig the sharp line → check if the rec book's odds are +EV → size the bet with Kelly.
Common Questions
What's considered a good EV%?
Most +EV bettors target 2% or higher. Even a 1% edge is profitable long-term if you can get enough volume. The higher the EV%, the faster your bankroll grows — but higher-EV bets are rarer.
Why do I need sharp book lines?
Sharp books have the most efficient odds because they accept action from professional bettors. Their de-vigged lines are the best estimate of true probability available. Without a sharp reference, you can't know if the rec book's odds are actually good.
Which de-vig method should I use?
Start with Power — it's the most accurate for most markets. It accounts for the fact that books tend to overcharge longshots more than favorites. If you want to be conservative, check the Worst Case row in the advanced section.
Is a -EV bet always bad?
From a pure math standpoint, yes — you're paying more than the bet is worth. But keep in mind the de-vig is an estimate, not an exact truth. A bet that's -0.5% EV might still be close to fair. The further negative the EV, the worse the bet.
Where do I find sharp book odds?
Pinnacle is the most commonly used sharp book. You can find their lines on their site directly, or through odds comparison sites like OddsJam, OddsBoom, or BettingPros that aggregate lines from multiple books.
Can I put this on my own website?
Yes! Click 'Embed This Tool' below the calculator for a copy-paste code snippet. It works on any website.
What is a positive EV bet?
A positive expected value (+EV) bet is one where the odds you're getting are better than the true probability of the outcome. If an event has a 40% true chance and the book is offering +200 (implied 33.3%), you're getting better than fair odds. Over time, consistently placing +EV bets is the only mathematically proven way to profit from betting.
What win rate should I expect with +EV betting?
Your win rate depends on the odds you bet, not just your edge. A +EV bettor taking mostly -110 sides might win 53-54% of bets. A +EV bettor on +200 underdogs might only win 35-38% but still profit because each win pays more. Focus on EV%, not win rate — a 52% winner on -110 is more profitable than a 60% winner on -300.