How to Calculate a Parlay

In summary, here are the steps to calculate a money line parlay:

Step 1: Apply a parlay factor to each team you want to bet on. For favorites, the parlay factor is: (money line + 100) / money line. For dogs, the parlay factor is: (money line + 100)/ 100.

Step 2: Multiply the parlay factors.

Step 3: Subtract one.

Step 4: Forget everything and use this handy Parlay Calculator.

Parlay Calculator Instructions

Step One: Enter the lines of your wagers into the column marked "Lines". Make sure you remember to put a minus ("-") sign in front of the favorites.

NOTE: Don't bother entering anything into the "Factor" column, because that takes care of itself and is only there for educational value.

Step Two: Enter your bet in dollars where it says "Bet". If you are only interested in finding out the payout factor, enter "1" as your bet.

Step Three: Click "Calculate Parlay".

Step Four: If you are planning on parlaying more than two or three games, get your head examined.
 


Team Lines Factor
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Bet ($)
  Winnings ($):

A parlay, as you know, is simply a payout based on the probability of two or more things happening. For baseball, what the bookie does is apply a factor to each game and then he can mix and match whatever games his players want and easily calculate the payouts.

The parlay factor is calculated differently for favorites and underdogs.

First we'll deal with favorites: For favorites, the parlay factor is calculated as: (money line + 100) / money line.

If you look closely, this is just the reciprocal of the chance of success. That is, if you liked X and his 70% chance of success (according to conventional wisdom and diligent research), then X's parlay factor would be 1/.70 or 1.43. If you liked another pitcher ("Z") in another game too (at -172, about a .632 chance), then Z's parlay factor would be 1/.632 or 1.58.

For underdogs, things are a bit easier.

The parlay factor is: (money line + 100) / 100. That is, if you also like Cincinnati with Q starting at +115, then Cincy's parlay factor would be (115+100)/100 = 2.15.

So now you've got three games that you'd like to parlay. In a perfect world, the payout for the parlay would be the three parlay factors multiplied out, or 1.43x1.58x2.15 = 4.86.

However, this isn't a perfect world, and if a three-teamer with a couple of good pitchers like X and Z in the mix paid out at 4.86, then there would be a lot of broke bookies. This just in: Bookies don't like going broke.

Therefore, the parlay payout equals the parlay factors multiplied out, minus one. So your three-team payout would be 4.86 - 1 = 3.86.

Simple.