Expected Value Calculator
Calculate the expected value (EV) of any bet. See whether the price pays more or less than your fair chance.
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Results
How to use this expected value calculator
Enter a stake, the American odds, and the win probability you believe is fair. The calculator turns the odds into the profit if the bet wins, and into the implied probability the price itself is charging. It then applies the expected-value formula: win probability times profit, minus loss probability times the stake. The dollar result is the average outcome per bet if you could place this same wager many times. A positive number means the price pays more than your fair chance deserves. A negative number means it pays less. EV is an average over repeats, not the result of the next bet, and a positive number can still lose.
What Is Expected Value in Betting?
Expected value (EV) is the average amount a bet would win or lose per bet if you placed the same wager many times. A positive number means the price pays more than your fair chance. A negative number means it pays less. Either way, the next bet can go the other way.
The Formula
EV = (Win Probability × Profit if you win) − (Loss Probability × Stake)
Worked example
Stake $100 at +150, with a 45% fair chance. Profit if it wins is $150. EV = (0.45 × $150) − (0.55 × $100) = $67.50 − $55.00 = +$12.50, which is +12.50% of the stake. The +150 price itself implies 40%. Your edge is 45% minus 40%, or 5 percentage points. Enter 100, +150 and 45 above and the calculator should show +$12.50, +12.50%, 40.00% and +5.00%.
New to the idea? Start with what is positive EV betting, the plain-English guide with this same example.
Frequently Asked Questions
What is an expected value calculator?
An expected value calculator turns a bet's odds, a fair win probability and a stake into the average result per bet. A positive number means the price pays more than that chance deserves. A negative number means it pays less. The result is an average over many repeats, and any one bet can still lose.
How do you calculate the expected value of a bet?
Multiply the fair win probability by the profit if the bet wins, then subtract the loss probability times the stake. At +150 with a 45% fair chance, that is (0.45 times $150) minus (0.55 times $100), which equals +$12.50 per $100 stake.
What is a good EV on a bet?
A small positive number on a liquid market is usually more meaningful than a huge number on a thin prop. Double-digit EV is often a stale price or an input that is off. The calculator reports the math for the probability you typed. It does not promise a result.
Where does the fair probability come from?
The win probability is your input, not something the odds contain. One way to get it is to devig a sharp book's line with the no-vig calculator, then use that fair chance here.
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