Calculating betting odds will depend on which odds format you used to place your bet: American, Decimal, or Fractional odds. Most bettors in the United States will use American odds. Each odds format represents the same thing: the percent chance of winning. To calculate this percentage, convert odds from American to Decimal. Then take 1/Decimal odds to calculate the implied chance of winning. You can also calculate the bets payout, profit, and more.