Sports Betting EV Calculator

How it's calculated

Decimal odds are 1 + odds / 100 for a positive American price, and 1 + 100 / |odds| for a negative price. Profit if the bet wins is stake × (decimal odds - 1). Expected value is win probability × that profit, minus the chance of losing × stake.

Illustrative example. A $10.00 stake at +150 with a 45% win chance profits $15.00 if it wins. Expected value is $1.25. The price itself implies 40%, so the edge against that implied chance is 5 percentage points.

What expected value means

Expected value (EV) estimates the average profit or loss of a bet if the same price and win probability were repeated many times. Positive EV does not mean the next bet wins.

How this calculator works

Enter American odds, your estimated win probability, and a stake. The tool converts odds to decimal price, compares your win% to market implied probability, and returns EV for that stake.

Pair EV checks with the no-vig calculator when you need fair two-way prices, then organize prop boards in Fantasy Forge. A promo price is a separate question: read odds boosts, then come back here with your win probability. The closing line value is the later check on the number you actually took.

FAQ

Does positive EV mean the next bet wins?

No. Positive EV only means your estimated win probability is higher than the market’s implied probability. Estimates can be wrong, and variance is real.

Do I need live odds feeds?

No. This calculator uses the odds and win probability you enter. It does not scrape sportsbooks or invent projections.

How is EV different from no-vig fair odds?

No-vig / fair odds remove bookmaker margin from a two-way or multi-way market. EV asks whether your own win-probability estimate beats the price you were quoted, including vig if you entered a raw sportsbook number.

Should I bet every positive-EV number this tool shows?

No. EV is only as good as the win probability you typed. Use bankroll limits, and do not treat a green EV figure as a reason to risk money you cannot afford to lose.