Expected Value Calculator for Sports Bets
Expected value is the average result of a bet if you could repeat it many times: win chance × profit minus loss chance × stake. Positive means the odds pay more than your win chance requires. It is only as good as the win chance you feed in.
Key facts
- Expected value is the probability-weighted average of the possible outcomes (Wikipedia, Expected value).
- Break-even win chance equals 1 divided by the decimal odds.
- A bet's expected value per dollar staked is win chance × (decimal odds) − 1.
Every bet has a price and a probability. If the price pays more than the probability needs, the bet has positive expected value; if not, it loses money on average, however it feels in the moment. The calculator turns your estimate into one number and shows how close to break-even it sits. It runs in your browser, sends nothing anywhere and forgets your numbers when you close the page.
Expected value calculator
Turn on JavaScript to use the calculator. The worked example below shows the same math by hand.
What you enter and what you get
You enter
- Odds: American, decimal or fractional.
- Your win chance (%): Your own estimate.
- Stake ($): an amount in dollars.
You get
- Expected value
- If it wins
- If it loses
- Your win chance
- Break-even win chance
- Fair odds at your chance
- Expected result over 100 such bets
How the calculator works
- Work out the profit if the bet wins: stake × (decimal odds − 1).
- Multiply it by your win chance.
- Subtract your lose chance times the stake.
- Divide by the stake to get the expected value as a percentage.
A worked example
A $100 bet at +120 where you think the true win chance is 50%.
| Item | Result |
|---|---|
| Expected value | $10 |
| If it wins | +$120 |
| If it loses | -$100 |
| Your win chance | 50% |
| Break-even win chance | 45.45% |
| Fair odds at your chance | +100 |
| Expected result over 100 such bets | $1,000 |
What the calculator leaves out
- Your win chance is an estimate, and a small error can flip the sign.
- Expected value is an average. One bet still wins or loses outright.
- It ignores limits, fees and how long your money is tied up.
How we checked it
Before it went on the page we checked it against two cases worked by hand: +100 at a 55% win chance on $100 has to give +$10, and -110 at its break-even 52.38% has to come out at about zero. The calculator is also run against thousands of odd entries such as blanks, zeros and huge numbers, so a bad entry shows a plain prompt and never a wrong number. The worked example above comes from the same code the calculator runs.
At a sweepstakes sportsbook
At a sweepstakes sportsbook the stake is in the site's sweepstakes currency, and what you can redeem depends on its rules, so expected value in coins isn't expected value in dollars. Read the redemption rules first. Gold Coins vs Sweeps Coins explains the two coin types.
Betting math is not betting advice. Only play with money you can afford to lose, and if gambling stops being fun, call or text 1-800-GAMBLER.
Frequently asked questions
What is a good expected value?
Anything above zero is positive, but small edges need many bets and an accurate estimate to matter. Treat results of 1 to 3% with caution.
How do I get my win chance?
From your own model or from removing the margin from sharp prices. The no-vig route is common, but it's still an estimate.
Does positive EV mean I will win?
No. A positive-EV bet still loses often. Only the long-run average moves.
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- Expected value, Wikipedia (read 2026-10-05)
- Implied probability, Wikipedia (read 2026-10-05)
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