Expected Value Calculator
Calculate the expected value of any decision. Input your probabilities and potential payouts to find out if a bet, trade, or prediction is +EV or -EV.
Ready to Calculate
Enter your probabilities and payouts, then click Calculate to see your EV analysis
How Expected Value Works
Expected Value (EV) is a mathematical concept that tells you the average outcome of a decision if you were to repeat it many times. A positive EV means you expect to gain over time, while a negative EV means you expect to lose.
The EV Formula
EV = (Win Probability × Profit) - (Loss Probability × Stake)
EV = Sum of (Probability × Net Payout) for each outcome
Where profit = payout - stake, and loss probability = 1 - win probability
Binary Mode
Simple win/lose calculations. Enter your estimated probability, stake, and payout to instantly see if a decision has positive expected value.
Multi-Outcome Mode
For scenarios with 3 or more possible outcomes. Define each outcome's probability and payout to get a complete EV analysis.
Odds Converter
Convert between American, Decimal, and Fractional odds formats. Automatically calculates the implied probability for your EV calculation.
Edge Calculation
See your edge — the difference between your estimated probability and the break-even probability. A positive edge means the decision is in your favor.
Frequently Asked Questions
What is Expected Value (EV)?
Expected Value is the average amount you would win or lose per decision if you repeated it many times. It's calculated by multiplying each possible outcome by its probability and summing the results. A positive EV (+EV) means the decision is mathematically favorable over time.
What does +EV and -EV mean?
+EV (positive expected value) means you expect to gain money over many repetitions of the same decision. -EV (negative expected value) means you expect to lose. Professional decision-makers focus on consistently making +EV choices.
How do I estimate win probability?
Win probability can come from historical data, statistical models, odds from bookmakers (use our odds converter), or your own analysis. The accuracy of your EV calculation depends heavily on having a realistic probability estimate.
When should I use multi-outcome mode?
Use multi-outcome mode when there are more than two possible results. For example: a poker hand where you could win, lose, or split the pot; or a prediction market with multiple resolution options. Each outcome gets its own probability and payout.
Can I use this for poker decisions?
Yes. For a poker call decision, enter your equity (win probability), the amount you need to call (stake), and the total pot you'd win (payout). The calculator will tell you if calling is +EV or -EV based on your numbers.
How does the odds converter work?
Enter odds in any format — American (+150, -200), Decimal (2.50), or Fractional (3/2) — and the converter shows all three formats plus the implied probability. You can then apply that probability directly to the EV calculator.
Disclaimer
This calculator is a mathematical tool for educational purposes only. Expected value calculations are based on the probabilities you provide and assume your estimates are accurate. Past results do not guarantee future outcomes. Always make decisions responsibly and within your means. This tool does not provide financial advice.
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