How to Read & Calculate Sports Odds

how to read and calculate sports odds

  • Understanding odds is the key to figuring out which bets are worth taking
  • Odds are displayed in a variety of different formats, but all are easy to understand
  • You can use odds to calculate the implied probability of a certain outcome in a sporting event

Understanding how to read odds is a crucial step to becoming a successful sports bettor. From determining how much money you want to wager to figuring out which bets offer the most value, it all starts with a solid understanding of the odds.

What Are American, Decimal, & Fractional Odds?

Odds are displayed in either American, Decimal, or Fractional formats, and serve two purposes:

  1.  They signal the implied probability of the outcome they are attached to
  2.  They indicate how much money you could win betting on that outcome

*Be careful relying on the odds alone when evaluating the probability an event will occur. Odds are influenced by more than the factors actually relevant to the outcome of the event.

Your sportsbook may manipulate the odds to incentivize bets on a certain side, and the sum of the probabilities for a single event will always surpass 100 percent because the sportsbook takes a cut that is baked directly into the odds.

Odds also reveal how much the book is charging to take your bet. You may hear bettors refer to this amount as “the juice” or “cut” or “vig(orish).”

American Odds Explained

When you see -150, +230, or any other three-digit number with a +/- in front of it, you’re dealing with American betting odds.

What Do the + and – Mean in Sports Betting?

The – and + on a sports betting line indicates both your prospective payout and whether you’re betting on the favorite or the underdog.

Negative numbers signify the favorite on the betting line. The negative number indicates how much you’d need to bet to win $100.

If the number is positive, you’re looking at the underdog, and the number refers to the amount of money you’ll win if you bet $100.

For example:

Example of American odds

Calculating Payouts with American Odds

In order to win $100 on the Penguins (favorites), you’ll need to wager $130. If you wagered $100 on the Senators (underdogs), you’d be set to win $110. 

You can use the formula below to calculate the potential payout  for any value you wish to wager.

If you bet $40 on Pittsburgh (-130), your equation would look like this:

Figure out American odds betting

  • Cross-multiply to get 130x = 4000, and then solve for “x”
  • x= 4000/130
  • x = 30.77

Therefore, if you wager $40 on Pittsburgh, you will win $30.77, and your return would be $70.77 (your original wager plus your winnings).

If you bet $40 on Ottawa (+110), your equation would look like this:

Figure out American odds beting

  • Cross-multiply to get 100x = 4,400, and then solve for “x”.
  • x = 4400/100
  • x = 44.00

Therefore, if you wager $40 on Ottawa, you will win $44.00, and your total return would be $84.00.

Calculating Implied Probability with American Odds

Implied probability refers to the likelihood of a particular outcome suggested by the odds. Figuring it out involves converting odds into a percentage, which indicates the likelihood that event will happen vs. the alternative. 

Of course, if you convert the odds available at your sportsbook into a percentage, they will include the “juice” or the “vig.” Factoring in the “vig,” the implied probability of the outcome of a game will be above 100%.

Implied probability is useful because if your estimate of the probability of an event occurring is different than a sportsbook’s you can and should adjust your bet accordingly.

Meet the authors

Matt McEwan
Dave F.
Sports Writer
William Hill
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