Expected value calculator
Expected value (EV) is the average profit or loss per bet if you could place the same bet many times: stake × (your win probability × decimal odds − 1). It depends entirely on the probability you enter, which is your own estimate. The calculator does not know the true chance of any result, and EV is a long-run average, never a promise about one bet.
Calculate EV
The win probability is yours. It is not supplied or checked by StatsNext. If your estimate is too high, the EV shown is too high by the same logic. The stake can be in any currency; results are in the same currency.
The formula
Profit if the bet wins = stake × (decimal odds − 1).
EV = p × profit if it wins − (1 − p) × stake = stake × (p × decimal odds − 1), where p is your win probability.
EV as % of stake = p × decimal odds − 1.
Break-even probability = 1 ÷ decimal odds: the win probability at which EV is zero.
A 100 stake at −110 (decimal 1.909) with your estimate of 55%. Profit if it wins: 90.91. EV: 0.55 × 90.91 − 0.45 × 100 = +5.00, or +5.00% of the stake. Break-even probability: 52.38%. At an estimate of exactly 52.38%, the EV is zero; at 50%, it is −4.55.
What EV does and does not tell you
- It is an average, not an outcome. A single bet either wins or loses; it never returns its EV. A positive-EV bet loses often, and a run of losses is normal even when an estimate is right.
- It is only as good as your probability. Estimating a sporting probability accurately is hard, and small errors matter: at −110, the difference between 52% and 55% is the difference between a negative and a clearly positive EV.
- The price already reflects the market. If your estimate is far from the no-vig probability, it is worth asking what the market knows that the estimate does not. The no-vig calculator shows what the prices imply without the margin.
- Pushes are not modelled. The calculator assumes a bet wins or loses. On a whole-number line where a push (stake returned) is possible, enter your chance of winning among the outcomes that do not push; the EV then applies to bets that do not push.
In the app, StatsNext shows a Model-Implied EV (Unvalidated) that uses its model estimate in place of your probability. The same caution applies: StatsNext’s predictive model has not demonstrated an advantage over sportsbook market probabilities.
Worked examples
| Odds | Your probability | Break-even | EV per 100 staked | EV % of stake |
|---|---|---|---|---|
| −110 | 50.00% | 52.38% | −4.55 | −4.55% |
| −110 | 55.00% | 52.38% | +5.00 | +5.00% |
| −110 | 60.00% | 52.38% | +14.55 | +14.55% |
| +150 | 35.00% | 40.00% | −12.50 | −12.50% |
| +150 | 40.00% | 40.00% | 0.00 | 0.00% |
| +150 | 45.00% | 40.00% | +12.50 | +12.50% |
| +400 | 15.00% | 20.00% | −25.00 | −25.00% |
| +400 | 20.00% | 20.00% | 0.00 | 0.00% |
| +400 | 25.00% | 20.00% | +25.00 | +25.00% |
Questions
Where does the win probability come from?
From you. The calculator does not know the true chance of any result and does not estimate it. It only shows what your estimate implies at the price you enter.
Does a positive EV mean I will make money?
No. EV is a long-run average that holds only if your probability is right. Any single bet, and any short run of bets, can lose. If your estimate is too optimistic, a positive EV on paper is a negative one in reality.
What is the break-even probability?
The win probability at which the bet’s EV is zero: 1 ÷ decimal odds, the same as the implied probability. Your estimate has to be above it for the EV to be positive.
How is this different from the StatsNext Model-Implied EV?
The arithmetic is the same. In the app the probability comes from StatsNext’s model instead of from you; those estimates are unvalidated and have not shown an advantage over sportsbook prices.
Arithmetic, not advice
These calculators do arithmetic on the numbers you enter. They do not know the true chance of any result, they do not predict outcomes, and using them does not make betting profitable. Betting involves financial risk, and no research or model makes gambling safe or removes that risk.
StatsNext is for people 18 and older. Being 18 or older does not mean sports betting is legal for you: follow the laws and legal gambling age requirements where you live. Never wager money you cannot afford to lose, and do not chase losses. If gambling stops feeling like it is within your limits, free and confidential help is available 24/7 from the National Problem Gambling Helpline: 1-800-MY-RESET (1-800-697-3738). More resources are on the Responsible Gambling page.
StatsNext is a research platform, not a sportsbook; it does not accept wagers or guarantee results (Research Disclaimer, Responsible Gambling).
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