Enter sportsbook odds, your estimated win probability, and stake to model EV dollars, ROI, edge, fair odds, payout, and Kelly sizing.
$100.00 at +150 with 45.00% win probability models +12.50% expected ROI.
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Use the same modeled price for Kelly sizing, odds conversion, or Boost EV Calculator checks without re-entering the core inputs.
Manual inputs only. No automated odds lookup, automatic bet placement, guaranteed outcome, or claimed true-probability model.
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An expected value calculator estimates the average profit or loss of a bet from the odds, your win probability estimate, and your stake. It shows whether the price is positive EV, how much edge you have versus break-even, what fair odds would look like, and how Kelly sizing would treat the same edge.
EV = (Win Probability × Profit if Win) - (Loss Probability × Stake)Expected value equals win probability times profit if the bet wins, minus loss probability times the stake. At +150 odds with a $100 stake, profit if win is $150. If your win probability is 45%, EV is 0.45 × $150 - 0.55 × $100 = $12.50.
Expected value is the average profit or loss a bet would produce if the same edge repeated many times. Positive EV means your estimated win probability is higher than the probability needed to break even at the offered odds.
The calculator does not supply a true probability. You must enter your own estimate from research, no-vig market math, a model, or another source. Bad probability inputs create bad EV outputs.
No. Positive EV describes long-run average value, not one-bet certainty. Variance, limits, line movement, voids, stale prices, and incorrect probability estimates can all change real outcomes.
Expected Value (EV)
The average amount you can expect to win or lose per bet over time.
Implied Probability
The probability of an outcome as implied by the betting odds, including the bookmaker's margin.
ROI (Return on Investment)
Your net profit divided by total amount wagered, expressed as a percentage.
Kelly Criterion
A formula for calculating the optimal bet size to maximize long-term bankroll growth.
Vig (Vigorish)
The commission a sportsbook charges on a bet, built into the odds.
Bankroll Management
The practice of managing your gambling funds to minimize the risk of going broke.
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