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Sports Betting Odds

Sports betting, whether you’re in Indiana or not, can be overwhelming. Even gamblers with experience in other games can be baffled by all the different types of wagers and calculations involved.

Part of the problem is that sports betting uses different odds more intensively than almost any other game of chance. Even if you’ve bet on games in a sportsbook before, you might be at a loss to articulate the meaning of all those three-digit numbers on the display board.

If interpreting the numbers you’re seeing is proving difficult, you’ve come to the right place. On this page, we walk you through what all the different odds mean, how the sportsbook figures them out, and how you can use them to your advantage.

What are odds?

Before we begin more complex discussions, we should probably establish what odds are. Simply put, odds are a numerical expression of the probability that an event will occur.

So, when you’re seeing a sportsbook’s published odds, you’re seeing a series of estimates that the professionals at the book have made regarding the outcome of a sporting event. The very basis of sports betting is your determination about how accurate those estimates are.

One of the more confusing aspects about odds is the fact that sportsbooks will use different formats to express the same estimate. Different parts of the world have their own preferences in this regard, so you need to be aware of the way odds may be expressed.


Fractional odds are probably the most common format that most people have seen for odds. Every American who attends school growing up learns about fractions, so it’s natural to gravitate towards this method of expressing probability.

For sportsbooks, it is far rarer to come across odds expressed as a fraction, particularly in the US. In most cases, you’ll run across fractions (if at all) on futures bets and live betting.

So, you may see the following odds for betting on the eventual winners of the next World Series:

  • New York Yankees: 3/1
  • Los Angeles Dodgers: 7/2
  • Houston Astros: 8/1
  • Atlanta Braves: 14/1

One thing to note about fractional odds is the story that the numerator and denominator tell. If the numerator is bigger than the denominator, then the team in question is the underdog or at a disadvantage.

Conversely, if the denominator exceeds the numerator, then the team is the favorite. In our example above, all four teams are underdogs against the field for winning the World Series.

However, if you saw a team or player listed as, say, 2 / 5, then the team or player is the favorite to win. Make sure to pay attention to how the fractions are expressed.


Another format that you may encounter is the decimal format. You are more likely to see decimal odds in sportsbooks overseas. To be frank, they are rather uncommon in American sportsbooks.

However, they are probably the easiest format to understand how much a winning bet will pay. The formula that sportsbooks use in relation to decimal odds is as follows:

Wager x Odds = Payout

The only tricky part about decimal odds is that figuring out how decimal and fractional odds relate to each other is not as simple as in normal mathematics. In fact, there’s an extra step that has to enter the calculation to make things come out properly.

The problem is that any sports bet payout has to include the original stake in its return. So, conversions from fractional to decimal odds require you to add 1, while decimals to fractions require you to subtract one.

So, for the New York Yankees example above, the team would be listed with 3/1 fractional odds, but with decimal odds of 4. Conversely, if the Dodgers were listed at 4.5, that would mean that they are 7/2 or 3.5/1 in fractional format.

Decimal odds = Fractional odds + 1

Fractional odds = Decimal Odds – 1

American Odds

The style of odds much more common in American sportsbooks is, naturally, the American format. This type of display makes extensive use of three-digit numbers that are either positive or negative.

This format is often called the moneyline interchangeably, due to the fact that moneyline bets are almost exclusively listed in this manner. So, the same futures listed above would probably appear in American sportsbooks like this:

  • New York Yankees: +300
  • Los Angeles Dodgers: +350
  • Houston Astros: +800
  • Atlanta Braves: +1400


The good news is that it is relatively easy to convert from the American format to fractional, if it makes you more comfortable to do so.

In order to make a set of American odds fractional, you will first need to look at whether the number is positive or negative.

If the number is positive (like above), simply divide the number after the plus sign by 100. Then, place a 1 under the number, and you have the fractional equivalent.

If the number is negative, you will need to divide 100 by the number to arrive at the proper fraction. Then, simplify the fraction as much as you can.

So, for example, a team at -350 would be the same as if they were listed at 100/350. Or, more simply, they’re going off at 2 / 7 odds.

What do the plus and minus signs mean?

By now, you’ve likely noticed that there are plus and minus signs next to various odds displays. They are always present in spread bets, moneylines, and most other options in American sportsbooks.

You may have already guessed from the explanation above, but the minus sign next to a number indicates that it is the event favored to occur.

So, a team with a negative number beside its name is the favorite to win the game. Conversely, a team with a positive number is the underdog.

For example, a typical moneyline opportunity might look something like this:

  • Los Angeles Lakers -450
  • Cleveland Cavaliers +320

In this example, the Lakers are favored to win the game, and the Cavs are expected to lose.

Plus and minus signs also show up for spread bets. The minus sign is the margin of victory that the listed team (the favorite) must meet or exceed for the bet to pay. The plus sign on a spread bet is the margin of loss that the listed team (the underdog) must not exceed.

So, a game might have the following spread in its listing:

Green Bay Packers -9.5 (-110)

Chicago Bears +9.5 (-110)

In this example, the Packers are favored to win the game by 9.5 points. So, in order for a bet on Green Bay to pay off, the team must beat the Bears by 10 points or more.

Conversely, the Bears must do their best to lose by 9 points or fewer. If they happen to win outright, that counts, too.

How do I know how much I will win?

In the example above, you may have noticed the -110 in parenthesis next to each team name. Since you’re betting on the point spread, it may not make sense why a moneyline is here.

However, what that number and moneylines themselves tell us is a story about the potential payout you will receive. The sign and value of the number gives us all the information we need to figure out what kind of day you might have.

The essential rule of payouts is as follows: A positive number is the amount a $100 bet can win, while a negative number is the amount you must bet to win $100.

So, what the -110 in the spread example tells us is that, regardless of the team you choose, you will have to risk $110 to win $100.

Now, you do not have to risk exactly $110 to make this kind of bet. You can bet whatever amount you want, but the payout will scale proportionally from this initial amount.

One last thing to remember before beginning to calculate the payout is your initial stake. The listed payout is only your profit on the bet, so you’ll get your money back with your winnings, too.

Therefore, here’s how to calculate your winnings from an American odds format:

Positive number (underdog bet)

Payout = Moneyline/100 x Initial Stake + Initial Stake


Initial Stake/Wager: $400

Moneyline: +190

Payout = (190/100) x 400 + 400 = $1160

Negative Number (favorite bet)

Payout = (100/Moneyline) x Initial Stake + Initial Stake


Initial Stake/Wager: 60

Moneyline: -205

Payout = (100/205) x 60 + 60 = $89.27

What if the game ties with the estimate?

As we said earlier, the basis of sports betting is a bettor wagering on the accuracy of the given odds. However, if a sportsbook is too good at its job and the game ends exactly as expected, then there’s a problem, because now there’s a tie.

As it turns out, there are a couple of ways that a book might deal with such an outcome.

The first approach is that if the game ends exactly on the spread or over/under, then the bet pushes. The sportsbook will then be forced to return all wagers to their original owners.

Of course, this outcome is a waste of the sportsbook’s time. After all, it only makes money off the vigorish (or vig) baked into the odds themselves.

So, the more common practice is to make sure that point spreads and totals are always set in 0.5 increments. In other words, the book makes it impossible to have a tie, since the game cannot end on a half-point.

The underlying theme about ties is that they are no harm to the player or the sportsbook. However, most sportsbooks don’t want to waste their time with refunds like that.

Why do the odds move sometimes?

If you’ve ever made a wager in a sportsbook, you may have noticed that the odds printed on your betslip may not always match the published odds on the same wager later. This movement may cause a bit of distress for you, and it’s understandable if you feel confused.

First and foremost, understand that your bet did not just get any worse or better. Whatever odds you have on your betslip are the odds at which the game will play for you, regardless of where the line moves.

However, it’s a bit strange that odds can move. After all, if the teams are still the same, then there’s no reason to believe that it will end differently than before.

Movement on the odds is due to the business model associated with sportsbooks themselves. One misnomer about sports betting is that you’re betting against the house – in truth, you’re mostly betting against people on the other side of the bet.

What a sportsbook would do on every single game – if it could – is balance out the potential payouts with the cash collected on the opposite side. In other words, if it’s going to have to pay 2:1 odds to one side, there had better be a $2 bet on the opposite side for every $1 wagered here.

Of course, there should be a bit extra on both sides for the book to keep. This amount – the vigorish, or vig – is the sportsbook’s profit.

So, moving odds are nothing more than a balancing act on the part of the sportsbook. It’s not always a bad thing for you, either.

After all, you might be sitting at a better position than others. Or, you might be able to put down a second bet if things look better now.

Types of Bets and the Odds They Use

If you are new to sports betting, you may be surprised to learn about all the different types of bets available online. Sportsbooks are no longer offering a few bets per game.

Instead, there can be hundreds of options on each and every match. It can be a bit dizzying, so here are the common types of bets you’ll encounter, along with the odds format that you’ll most likely find.

Point Spread

Spread bets are wagers on the eventual margin of victory. You will guess whether the favorite will win by more or the underdog will lose by less than the estimate.

Odds format: Single or double-digit spreads that are either positive or negative. Payout listed in American odds format.


Indiana @ -8 (-110)

Notre Dame @ +8 (-110)


The moneyline is a straight wager about which team will win, regardless of margin. However, the odds affect the end payouts that players can expect to receive for winning bets.

Odds format: American


Indiana -195

Notre Dame +145

Totals (Over/under)

Totals bets are wagers regarding the total amount of points that both teams will score in the game. Which team wins is irrelevant. This bet is more commonly known as the “over/under” because bettors are guessing whether the actual total will be over or under the sportsbook’s estimate.

Odds format: Over or under choices that are either greater than or less than the estimate. Payout listed in American odds format.


Indiana vs. Notre Dame

O 163.5 (-108)

U 163.5 (-112)


Futures bets are cumulative speculations about the end of a season of play. They usually pertain either to team or player achievements, such as championships or excellence awards.

Odds format: American or fractional


Favorites to Win the NBA Championship

Los Angeles Lakers: +200

Milwaukee Bucks: +240

Los Angeles Clippers: +300


Propositions, or prop bets, are a mishmash group of almost every other type of bet. They tend to involve partial game results or events ancillary to the outcome of the game.

Odds format: American


Super Bowl Coin Toss

Heads: -110

Tails: +105

Live betting

Live betting is a form of proposition wager that takes place after a game has begun. Technological advances have allowed an exceptional level of granularity to become available in live betting. Thus, live betting usually accounts for the majority of wagers in a game.

Odds format: American or fractional


Team to Win 1st Half (if Indiana is in the lead)

Indiana: -150

Notre Dame: +185


Parlays are combination bets that fold multiple wagers into a single bet. They tend to be high-risk, high-reward ventures because it is necessary to win every single part of the parlay (known as “legs”) to win the entire bet.

Odds format: American


A player bets the moneyline on a night’s NBA games. He takes the favorite in each game, but because of the aggregate risk, the entire parlay still offers him odds at +225.