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Sports Futures Calculator
To use this calculator, enter the the odds each event pays. Leave unneeded fields blank. Odds should be entered on a "to one" basis or American odds. If American odds are being used (like +300 or -500), check the American odds box. Then click "calculate." The calculator will calculate the house edge, assuming every bet has the same house edge. This calculator is intended to calculate how much juice a sports book takes out of its futures wager, so that you may compare who is offering the best odds overall.
For example, consider these William Hill odds for the 2016 Republican presidential nominee (taken August 3, 2014 -- note that Trump paid 66 to 1).
If you put these odds in the calculator, you'll get a house edge of 23.44%. Remember to convert fractions, like 9/2=4.5.