Sports odds are numerical expressions of the expected outcomes and the probability of various events occurring throughout the game. They indicate which side is more likely to win, and by how much.
Sports odds can come in a variety of formats, but each format is simply a different way to express the same thing.
What Are Sports Odds?
Sports odds assign a number associated with the frequency of how often that team is expected to win. The odds are not predictions on exact scores, but rather on how often each margin of victory is expected to occur.
In short: The stronger the number is for the favorite, the more likely it is expected to win.
What Do the “+” and “-” Numbers Mean?
In many formats, the plus and minus signs indicate which team is favored and by how much.
- The plus sign (+) is assigned to the underdog, and they are considered less likely to win.
- The minus sign (-) is given to the favorite, and the larger the number, the more heavily favored they are.
American Odds (U.S. Format)
American odds are the most common odds format in the United States. They are based around the number 100, using plus or minus signs to show the relative probability of victory for each team.
Positive American Numbers (+)
The positive numbers are assigned to the underdog, with the larger numbers assigned to the bigger underdogs. A team with +120 odds is perceived as less likely to win, but the odds of an upset are still high.
Alternatively, a team with +600 odds to win will only prevail a very small fraction of the time, as they are seen as a big underdog.
Negative American Numbers (-)
The negative numbers are given to the favorite, with the larger numbers implying a more confident expectation they will win. Just like the underdog, a -150 favorite is more likely to win, but not by much, while a -1000 favorite will win an overwhelming majority of the time.
Fractional Odds (UK Format)
Fractional odds are common in the United Kingdom and are displayed as ratios, such as 6/1, 2/3, or 7/2.
The fraction represents the strength of the given side. The larger the fraction, the less likely they are to win. Any fraction over 1/1 means the outcome is considered less likely, while a fraction lower than 1/1 is considered more likely.
For example, two teams with 5/1 odds and 2/1 odds are both considered underdogs, but the 2/1 underdog is much more likely to win than the 5/1 underdog. Larger first numbers suggest a low probability, while larger second numbers, like 1/6, imply a higher probability.
- ALSO CATCH: What is an Underdog in Sports?
Decimal Odds (European Format)
Decimal odds are used all across the world, including Europe, Canada, and Australia. Decimal odds are the most straightforward, as the number represents a multiplier for the team predicted.
- A 1.20 multiplier is low, which means the team is expected to win a large percentage of the time.
- 3.25 odds, however, offer a tantalizing multiplier, indicating that the chosen team is seen as less likely to win.
- Odds of 2.00 represent a 50% chance of winning, while higher odds mean a lower chance of winning.
Converting Odds to Implied Probability
Probability from American Numbers
With American odds, the method to find the implied probability changes depending on whether you are taking the favorite or the underdog. With the favorite, you must divide the number by itself plus 100.
- For example: a -200 favorite’s implied probability would be calculated by dividing 200 by 200+100 to get 0.66. That means a -200 favorite has a 66% chance of winning.
For the underdog, divide 100 by the odds number plus 100.
- For example: a +300 underdog’s implied probability is 100 divided by 300+100, which equals 0.25. That means a +300 underdog has a 25% chance of winning the game.
Probability from Fractional Numbers
For fractional numbers, you can find the implied probability by dividing the first number by the sum of both numbers.
A team with 1/3 odds will have an implied win probability of 3 divided by 1+3, which equals 0.75 or 75%. If the first number is larger than the second, the same formula can be used to calculate implied probability.
Probability from Decimal Numbers
The probability of decimal numbers can be calculated by dividing 1 by the decimal value. If a team has 3.00 odds to win, you divide 1 by 3 and get 0.33, or 33%. If the decimal odds are 1.20, you divide 1 by 1.2 to get 0.8, or 80%.
- ALSO CHECK OUT: How Point Spreads Work
Why Odds Change
The odds are constantly being adjusted by the oddsmakers right up until the game gets underway. There can be dramatic shifts in odds for a variety of reasons, including injuries, public interest, performance trends, and late-breaking news.
One of the primary goals for the oddsmakers is to keep the action close to 50/50 on each side. If one side is getting more than 50% of the predictions, the oddsmakers will often shift the odds to entice more predictors into taking the other side.
How Odds Are Used in Sports Analysis
Odds are used to create a quick snapshot of which team is expected to win, how often they will win, and what the expected margin of victory is. The odds are often an accurate reflection of these facts and can usually give a better understanding of how the game is expected to go, rather than simply looking at the teams playing.
The odds can identify mismatches, project score margins, and effortlessly compare team strengths.
Common Odds Vocabulary
| Term | Meaning |
| Favorite | The team or outcome is viewed as more likely to occur |
| Underdog | The team or outcome is viewed as less likely to occur |
| Line Movement | Changes in the odds over time |
| Pick’em | No clear favorite; both sides close to 50/50 odds |
| Opening Line | The first set of odds released for a matchup |
| Closing Line | The final set of odds immediately before the event begins |
| Juice or Vig | The built-in adjustment to balance platform exposure |
| Implied Probability | The probability a team will win based on the odds |
How to Use Odds in Real Life
There are many ways to use odds other than making predictions. They include fantasy sports, game previews, power rankings, prediction models, and day-to-day knowledge. Knowing how to read the live sports odds gives you an accurate assumption of what may happen in any situation.
Key Takeaways
Before making a single prediction on any sporting event, knowing the odds for each side is the most important thing.
The Lakers will almost always be favored to beat the Washington Wizards, but incredibly lopsided odds may make the underdog an appealing option. The different formats all express the same ideas, allowing you to pick the format that makes the most sense to you.
Having a deep understanding of what the odds mean, what they represent, and how to unlock the implied advantages buried within the numbers will allow you to make more informed choices in the long run.
FAQs
What do sports odds mean?
Sports odds show the likelihood of a team or outcome winning. They indicate which side is favored and which is the underdog.
What do the plus (+) and minus (−) symbols mean?
The minus sign (−) represents the favorite, while the plus sign (+) represents the underdog.
What are the main types of sports odds?
The three main formats are American odds, decimal odds, and fractional odds.
What are decimal odds?
Decimal odds show the total return multiplier. For example, 2.00 odds equal a 50% probability.
What are American odds?
American odds use + and − numbers to show favorites and underdogs and are common in the United States.
What are fractional odds?
Fractional odds are written as ratios like 5/1 or 2/3, showing the potential profit compared to the stake.
Why do sports odds change?
Odds change due to factors like injuries, team news, and prediction activity.
How do you convert odds to probability?
Probability can be calculated from odds using formulas based on the odds format.
