EV Calculator
The EV Calculator helps you determine whether a bet has positive expected value. By comparing your estimated win probability against the sportsbook odds, the tool tells you exactly how much you can expect to gain or lose per dollar wagered over the long run. A positive EV means the bet is in your favor; a negative EV means the sportsbook has the edge.
This tool is available to all users at Tools > EV Calculator (/tools/ev-calculator). All calculations run entirely in your browser — nothing is sent to the server.
How to Use
Section titled “How to Use”Enter your inputs in the calculator form:
| Input | Label | Description |
|---|---|---|
| Odds Format | Odds Format | Choose between American, Decimal, or Fractional. Your selection is saved to localStorage and shared across all calculator tools. |
| Odds | Odds | Enter the sportsbook odds for your bet. When Fractional is selected, two input fields appear separated by a / divider. |
| Win Probability | Win Probability (%) | Your estimated probability that the bet wins, from 0 to 100. The sportsbook’s implied probability is shown as a hint below the field for comparison. |
After filling in the fields, results update instantly.
Understanding the Results
Section titled “Understanding the Results”The results section is color-coded: green when EV is positive (you have an edge), red when EV is negative (the sportsbook has the edge).
| Output | What It Means |
|---|---|
| Expected Value (EV) | The large headline number. Positive means profitable long-term; negative means you lose money over time. |
| EV per $100 bet | The dollar amount you expect to gain or lose for every $100 wagered. Makes it easy to compare across different odds. |
| Edge | Your advantage (or disadvantage) expressed as a percentage. A 5% edge means your probability exceeds the implied probability by 5 points. |
| Implied Probability | The win probability baked into the sportsbook odds. Compare this against your own estimate to see where the value lies. |
A Show Math collapsible section displays the full formula with your actual numbers substituted in, so you can verify every step of the calculation.
How It Works
Section titled “How It Works”The expected value formula is:
EV = (win_probability x net_profit) - (loss_probability x stake)EV% = EV x 100Where net_profit is the amount you would win (excluding the returned stake), loss_probability is 1 - win_probability, and stake is the amount wagered. When EV% is positive, the bet has a mathematical edge in your favor.
- Finding your win probability is the hard part. Use the model scores from the Prop Explorer and your own research to estimate how likely a bet is to hit.
- A positive EV does not guarantee a win on any single bet. It means that if you placed this bet many times, you would come out ahead on average.
- Once you find a +EV bet, use the Kelly Calculator to determine how much of your bankroll to risk on it.
- Compare the implied probability from the odds against the model’s estimated probability to quickly spot value.