This calculator determines fair parlay odds.
Inputs

Outputs
 Mathematical Odds: These are the imagined odds that suggest a zero vig (or bookmakers fee) on the parlay.
 True Parlay Odds: The underlying bets implied odds.
 True Parlay Risk/Win Amount: The risk or win currency value that is based on the true parlay odds.
 Premium Paid Over Mathematical Odds: The extra amount paid by the bettor as a percentage of the parlay amount. This is over and above the amount implied by the underlying bets. A negative number would suggest that the parlay was offered with a discount.
The parlay bet (which is also known as an accumulator bet, typically in the United Kingdom) is a bet that is placed based on the outcome of several bets combined.
Each bet must win in order for the parlay to pay out. If at any stage one of the bets should be lost then the whole parlay is lost. If one part of the parlay pushes then it is treated as it never existed, for example a 4 team parlay would then become a 3 team parlay and so on. Parlays offer greater rewards but the risk is also bigger.
The parlay calculator determines not only the parlay payouts but also the associated premiums if given a set of underlying bet odds.
Note: The calculator accepts both US and decimal odds. For Decimal odds greater than or equal to 100, preface the odds with either a “0″ or a “d”. For example, decimals odds of 200.0000 can be entered as either “d200″ or “0200″.