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Your edge analysis appears here
Set your odds, probability and bankroll, then click Calculate.
Calculate expected value, optimal Kelly bet sizing, and closing line value for any sports bet — NFL, NBA, EPL, and more. 100% free, runs in your browser.
Set your odds, probability and bankroll, then click Calculate.
The EV calculator takes three inputs: your odds (in American format), your estimated win probability, and your bankroll. It outputs expected value per $100 wagered, your edge over the book, and your optimal Kelly Criterion bet size. Use it before placing any bet to verify you have a genuine mathematical edge — not just a gut feeling.
Enter the American odds for the bet you're evaluating. If the sportsbook shows -110, enter -110. If you see +150, enter +150. The calculator converts these to decimal format internally. American odds of -110 mean you need to bet $110 to win $100; +150 means a $100 bet wins $150.
This is the most critical input and the hardest to get right. Your win probability estimate should come from either: (a) the no-vig odds at a sharp sportsbook like Pinnacle or Betfair exchange, or (b) your own statistical model. Never use gut feel here — even a 2% error in probability can flip a bet from +EV to -EV.
To get no-vig probability: take the odds from a sharp book, strip the vig using our vig calculator, and use the resulting implied probability. For example, if Pinnacle has -108/-108 on a 50/50 market, the no-vig probability is 50% for each side.
The Kelly Criterion calculates the mathematically optimal fraction of your bankroll to bet. However, Full Kelly produces very high variance and requires extremely accurate probability estimates. Most professional bettors use Half Kelly (50% of the Kelly recommendation) as their standard. Quarter Kelly is appropriate for beginners or when you have low confidence in your probability estimate.
If you know the closing line for this bet, enter it. CLV measures whether the odds you got were better than where the market settled. Getting better-than-closing-line odds consistently is one of the strongest indicators that you're finding genuine edges. A positive CLV (you got better odds than the closing line) means you beat the market.
Most serious bettors target a minimum of +3% to +5% EV per bet. Anything below +2% is in the noise range — a small error in your probability estimate easily flips it negative. The higher your confidence in your probability estimate, the lower EV you can profitably pursue.
At scale — say 500 bets per year — a consistent +4% EV edge produces significant profits regardless of variance. The math works in your favour as long as you stay disciplined about only taking +EV spots.
The full Kelly formula maximises long-term growth rate mathematically but creates extreme short-term variance. Betting Full Kelly means accepting swings of 50%+ of your bankroll. Most professional bettors use Half Kelly, which sacrifices about 25% of long-term growth but cuts variance by 75%. Quarter Kelly is for when you're uncertain about your edge estimate — it keeps bet sizes small enough to survive being wrong.
The EV formula works identically across all sports. Whether you're betting an NFL spread, an NBA prop, an EPL match result, or an ATP tennis match, the calculation is the same: your probability versus the book's implied probability, multiplied by the stake. The key is always probability estimation — and that's where sport-specific knowledge and sharp reference lines matter most.
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