This is a parlay odds calculator. It takes the American odds for multiple bets, converts each into its implied probability, and then multiplies them together to calculate the probability of the entire parlay winning. It then converts that probability back into “fair” American odds, so you can see what the true price of the parlay should be.

Each American price is first turned into an implied probability:

• Positive odds (e.g. +200) → 100 / (odds + 100)

• Negative odds (e.g. -150) → |odds| / (|odds| + 100)

Those probabilities are multiplied together to get the parlay probability. Finally, that probability is converted back into American odds.

Sportsbooks don’t always offer parlay odds that perfectly reflect the fair price. By comparing the calculator’s “fair odds” to what your sportsbook offers, you can instantly see if the parlay is overpriced or fairly priced. The price will still include the vig, but makes sure the sportsbook isn't short-paying you on top of it.