Expected Value (EV) Calculator
Use this free expected value calculator to find out whether a bet is plus-EV before you place it. Enter the odds, your estimated win probability, and your stake, and the tool shows the expected value in dollars and percent, your break-even probability, and your edge over the book. It works with American or decimal odds.
What Is Expected Value in Betting?
Expected value, or EV, is the average amount a bet would win or lose if you could place it over and over. A positive expected value (plus-EV) bet makes money over the long run, while a negative EV bet loses. Sharp bettors ignore whether a single bet wins and focus on whether it was plus-EV. The expected value calculator above turns your odds and win probability into a clear dollar figure.
How to Use the EV Calculator
Choose your odds format, enter the price, then enter your honest estimate of how often the bet wins as a percentage. Add your stake and the calculator returns the expected value in dollars and as an ROI, your break-even probability, and your edge over the sportsbook. If the expected value is positive, the bet is plus-EV.
Worked Example
Say a bet is priced at +120 (decimal 2.20) and you believe it wins 50 percent of the time. The break-even probability is 1 divided by 2.20, or 45.45 percent, so your 50 percent gives you an edge of about 4.55 percent. The expected value per dollar is (0.50 times 2.20) minus 1, which is 0.10. On a $100 stake that is a plus-EV of $10, a 10 percent expected ROI. Fair odds for a 50 percent chance would be even money, or +100.
Why Expected Value Beats Chasing Wins
A plus-EV bet can still lose, and a negative EV bet can still win, on any given night. That is why judging your betting by recent results is misleading. Over hundreds of bets, your bankroll tracks the expected value of your decisions, not your luck. Grading every bet by its EV, win or lose, is how you know whether your process is actually beating the market.
Free Printable EV Worksheet
Want to grade a bet by hand? Download the free printable expected value worksheet to record the odds, your win probability, and your stake, then compute the break-even probability, your edge, and the dollar EV step by step.
Download the EV Worksheet (PDF)
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Expected Value Calculator FAQ
What is an expected value calculator? An expected value calculator works out the average profit or loss of a bet based on the odds and your estimated win probability. A positive result means the bet is plus-EV and profitable long term.
How do you calculate expected value in betting? Convert the odds to decimal, multiply by your win probability, and subtract 1. That is the expected value per dollar staked. Multiply by your stake for the dollar figure.
What is a plus-EV bet? A plus-EV, or positive expected value, bet is one where your estimated win probability beats the break-even probability implied by the odds, so it makes money over the long run even if it loses sometimes.
What is break-even probability? Break-even probability is 1 divided by the decimal odds. It is the win rate you need just to break even at that price. Beat it and the bet is plus-EV; fall short and it is negative EV.
Can a plus-EV bet still lose? Yes. Expected value is a long-run average, so any single plus-EV bet can lose. Over many bets, though, consistently taking plus-EV bets is what grows a bankroll.
