Odds communicate both a potential payout and a market-implied break-even probability.
Positive American odds
For positive odds, divide 100 by the odds plus 100. A price of +150 converts to 100 ÷ 250, or 40%. Before considering fees or other market effects, a bettor must win more than 40% of equivalent wagers to have positive expected value at that price.
Negative American odds
For negative odds, divide the absolute value of the odds by that value plus 100. A price of −150 becomes 150 ÷ 250, or 60%. Negative odds indicate that the potential profit is smaller than the stake.
Implied does not mean true
Implied probability is the break-even percentage embedded in the price. It is not a guarantee, a forecast, or necessarily the sportsbook’s unadjusted belief. Sportsbook margin means the implied probabilities across all outcomes can add to more than 100%.
Use it as a comparison point
Expected value starts by comparing the implied break-even percentage with a carefully formed probability estimate. The larger the gap, the more valuable the price may appear—but uncertainty in the estimate also matters.
EVBet provides educational calculations, not betting recommendations. A mathematical edge depends entirely on the accuracy of the probability entered.