Calculate whether a bet has positive or negative expected value
Calculate EV, edge, and break-even probability
Positive expected value
Common EV scenarios
Monte Carlo simulation with 1,000 iterations
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Understanding the expected value formula
For a $100 bet at +150 odds with 45% estimated win probability:
Key concepts at a glance
Expected Value (EV) = (Win Probability × Profit) - (Loss Probability × Stake). A +EV bet has positive expected return. At +150 odds (40% implied), if you estimate 45% true probability, EV = (0.45 × $150) - (0.55 × $100) = +$12.50 per $100 wagered. Consistently finding +EV bets is the key to long-term profit.
Important concepts to understand
Common questions about expected value
Expected value (EV) is the mathematical expectation of what you'll win or lose per bet over the long run. It accounts for both the probability of winning and the payout. A bet is +EV when your expected return is greater than your stake.
True probability estimation requires research: team statistics, injury reports, weather, historical matchups, and market movement. Many use power ratings, models, or simply compare lines across multiple sportsbooks. If you can't estimate probability better than the market, you likely don't have an edge.
Win rate alone is misleading. A 60% win rate on -200 favorites loses money (break-even is 66.7%). A 35% win rate on +250 underdogs makes money (break-even is 28.6%). EV captures both probability AND payout, giving the true picture of profitability.
Professional bettors typically find 2-5% edges. A 3% edge is considered good. Finding consistent 5%+ edges is excellent and rare. Remember that even small edges compound significantly over thousands of bets. A 2% edge at $100/bet over 5000 bets = $10,000 expected profit.
Yes, in the short term. Variance (luck) affects results over small sample sizes. A coin flip is 50/50, but you might flip heads 7 times in 10 flips. Over thousands of +EV bets, your results converge toward the expected value. This is why bankroll management is crucial.