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How Betting Odds Work

For anyone new to online sports betting, making a wager for the first time might be somewhat intimidating. Online bookmakers use specific terminology to make them sound like experts in their fields of expertise.

However, even the most seasoned sports handicappers don’t know everything about the activity. The following will cover all the sports betting odds information and terminology every bettor needs to know to succeed.

Basics of Betting Odds

The primary purpose of betting odds is to indicate how much a player will win from a successful bet. Then, the bookmaker balances the numbers to ensure it gets enough action on both teams for any event. There are three common formats of betting odds which are American odds, fractional betting odds, and decimal betting odds.

Online sportsbooks will set a default odds format based on the player’s location, with most allowing them to change it to their personal preferences. This can be done directly on the provider’s site, or players can use one of the many odds converters online. Here are the different formats and how they work:

American Odds

Here’s an example of how a contest with American odds would look:

New York Knicks +150 Los Angeles Lakers -175

The odds show the player two things; how much you must wager to win $100, indicated by the plus sign, and how much you will win from a $100 wager, indicated by the minus sign. In this example, if the player wagers on the Knicks to win, a $100 bet would win $150. On the other hand, if you bet on the Lakers to win, the bet must be $175 to win $100.

The positive and negative numbers used in the American format make it easy to determine the favored team. The negative number indicating the favorite and the positive number showing the underdog.

The payout differs depending on which side of the betting line you’re on. In this example, instead of the lines being +150 and -150, they are at +150 and -175. The difference in these numbers being called the “juice” or “vig.”

This is the amount the bookmaker charges players for making a bet. The vig ensures that sportsbooks make money from every wager that is placed. The greater the vig, the less value in the bet, so it’s essential to sometimes shop around for better lines at a sportsbook with as little vig as possible for your wagers.

Decimal Odds

Also known as European odds, decimal odds are displayed in decimal format. They’re different from American odds in that they show the total money returned instead of just the winnings for any wager. In this example, we have the same two teams with odds displayed in decimal format:

New York Knicks 2.500 Los Angeles Lakers 1.571

To calculate the total money return, multiply your stake by the decimal odds shown. For example, if a player were to bet $100 on the Knicks to win, the total winnings would be $250.

Generally speaking, if the number is smaller than 2.0, such as the Lakers, they are considered the favorite. If the number is greater than 2.0, they are considered the underdog.

Fractional Odds

Fractional odds, also known as British odds, are usually written with a slash. For example, a fractional listing of 2/1 means the player would win $2 for every one dollar wagered, plus the amount of the original stake of one dollar. The odds are the ratio of the won to the initial bet. Meaning the stake is also received in addition to the profit made on the bet.

So, using the same two teams as an example, in fractional odds, the lines look like this:

New York Knicks 37/25 Los Angeles Lakers 100/173

If we wanted to bet $100 on the Knicks at 37 to 25, we would receive back the $100 stake and the $140 profit, resulting in a total return of $248. As far as determining who the favorite is using fractional odds, just look at the numbers on either side of the fraction.

In general, if the numerator is smaller than the denominator, then that team is considered the favorite, which in the example would be the Lakers. Conversely, the team with a denominator higher than the numerator is regarded as the underdog.

Popular Betting Markets

With a basic understanding of the different types of betting odds, the knowledge can now be applied to the most popular betting markets. There are three major bets available in any sports market:


A moneyline wager is the most popular way players bet on sports. A moneyline bet is a wager on which team the player believes will win the contest. It doesn’t matter how they win, by how many points, or how long they take to win. The previous Knicks vs.Lakers odds was an example of a moneyline bet. All the player needs to do is pick the winner. It’s as simple as that.

There are two main reasons why casual and professional bettors like making profits on moneyline bets. The first is that they’re easy to make, with the chances of making a mistake with this type of wager being a lot lower, and there’s often an excellent value to be found from plays that sometimes go unnoticed. Anyone can pick a winner of a sporting event, so all that’s left is deciding whether or not the risk is worth the reward.

The second reason is it’s easier to find value in the markets when making moneyline bets. This is because there aren’t multiple complex layers to sift through to see if your pick will make money over the long run. Instead, by doing a few simple calculations, players can figure out whether there’s value in the bet.

Point Spreads

The point spread bet is the second most popular way players like to bet on sports. The point spread is the margin of victory set by the bookmaker between the two teams or competitors. Before posting the lines, they determine the favorite and how many points they are favored by.

To be more specific, a point spread bet is a wager in which the player picks which team will do better than their expected performance. The bookmaker will set the line based on how well it thinks each team will play during the game. The player will then choose which team they believe will perform better than the set betting line.

The points spread betting line is usually reserved for sports and leagues in which a high number of points are scored, such as the NFL and the NBA. Here’s an example of a point spread line for an NBA game between the Knicks and Lakers:

New York Knicks (+3.5) -110 Los Angeles Lakers (-3.5) -110

The negative sign next to the Lakers’ margin shows that they are considered the favorites by the bookmakers and should win by three or four points. The betting line is set at 3.5 points. On the other side, the positive sign next to the Knicks indicates that the bookmakers consider them the underdogs in the game.

In this scenario, a bet on the Lakers means if they win the game by four or more points, the bet is a winner. This is known as “covering the spread.” Conversely, if the Lakers win by three points or less, the bet will lose. On the other hand, if you bet on the Knicks and they lose by less than four points or win the game, you win the bet. However, if the Knicks lose by four points or more, the bet is a loser.

Bookmakers will often use half-points in the betting lines to avoid the possibility of a tie, which is when the margin of victory lands directly on the betting line. When the odds are not set to a half-point, and the match finishes with the margin of victory equal to the betting line, you don’t win the bet, but the original stake will be refunded.


Totals betting is the third most popular way to bet on sports. Also known as over/under betting, a totals bet is a wager on the total number of points, runs, or goals scored in a game. This bet is in no way related to the actual result as far as a winner and a loser, which makes it different from betting on the moneyline and the spread.

It also makes no difference if only one team scores all of the points in the game. The only thing that matters is the total number scored by both teams combined.

Here’s another example using an NBA game:

Over (216.5) -110 Under (216.5) -110

As seen above, the actual bet doesn’t include the two teams competing, only the number of points. In the example, the bookmaker believes that there will be 217 points scored. They then drop this total down by a half-point, giving players the chance to bet on more than 217 points being scored to hit the over, or 216 points or less to win a bet on the under.

As was mentioned before, bookmakers will use half-points in totals to avoid a tie scenario. When the line isn’t set to a half-point and the contest finishes with the total points equal to the betting line, the bet is not a winner, but the original stake is returned to the player.

Movement of Lines

When learning about betting lines and odds, players should also be familiar with why they constantly change to find value more easily. Before players can understand how and why betting lines move, they need to better understand what’s happening behind the scenes of their favorite sportsbook.

While bookmakers are offering different wagers for players to make, they aim not to gamble at all. The purpose of any sportsbook is to come out ahead no matter which side wins a wager, meaning the bookmaker always wins.

For example, the Knicks are playing the Lakers, and $20 is wagered on the game, with the total amount bet split between the two teams. If the Knicks win, the sportsbook uses the money wagered on the Lakers to pay the winning bets.

The same thing works in reverse if the Lakers win the contest. This results in the bookmaker not losing any money on the game, no matter which team wins.

The way sportsbooks assure themselves of making money is by adding the “juice” or “vig”. This is a small percentage of profit taken when the wager is made. Instead of paying out $10 on a winning bet, the bookmaker may payout odds set so the payout is $9.

By setting payout odds of -110 on both sides of an event, no matter which team wins, the winning $10 bet would pay back $9.09 in winnings. However, if the bookmaker adjusts the odds to take in the same amount in wagers on both sides, they make the extra $0.91 in profit no matter the game’s outcome.

Why Sportsbooks Move Lines

This is why sportsbooks will move the line. After setting the initial line to something the bookmaker thinks will get equal action on both sides, the lines will move along with the bets that are placed and are adjusted so the sportsbook can keep the payout amounts they will owe the winners even on both sides.

A lot of betting on one side is why betting lines will shift. It’s sometimes more apparent when the lines first come out, as professional players known as “sharp” bettors like to take advantage of bad lines when they are first posted.

A couple of other reasons lines may move is due to injuries to key players and stories in the media. For example, if the best player on a team gets hurt before the big game, the sportsbooks will be less confident in them to win.

Since players will place more bets on the opponent, the bookmaker will move the line to even out the betting on both sides. People trying to bet on the opponent before the line moves.