Understanding how to read betting odds is critical to your chances of success at a sportsbook, so read our guide to find out more.
How do odds work exactly? Betting odds reflect the chances of an event happening. Many of the operators we work with display prices for a wide range of sports that have multiple outcomes per match.
While knowing the math is key to understanding betting odds, most top online sports betting sites, such as Unibet and bet365, have bet calculators to help determine your potential winnings.
Most sportsbooks advertise odds in decimal, American, and fractional odds. For sportsbooks in the US, American odds are the default.
What are good odds? They vary from one site to another as sportsbooks post marginally different prices. To find good odds, you will need to use our comparison tool, which highlights the odds advertised by each sportsbook so you can get more value from your wagers.
A key part of knowing how to read betting odds is assessing the implied probability. Otherwise known as capping, bookmakers have various strategies to determine the odds, such as reviewing statistics and tactical analysis.
You could bet on Tottenham to beat Manchester United at Old Trafford in a Premier League game. The odds may be 3/1 for Tottenham to win. To calculate the implied probability, you can convert the odds into decimal, which would be 4.0 in this case. This would have an implied probability of 25%.
Odds come in three forms: fractional, decimal, and American odds. Converting to implied probability as a percentage makes it easier for players to understand their bets. Bookmakers can convert odds, but our table will help bettors understand how to read odds.
Implied Probability |
Fractional Odds |
Decimal Odds |
American Odds |
|---|---|---|---|
| 99.01% | 1/100 | 1.01 | -10000 |
| 80% | 1/4 | 1.25 | -400 |
| 75% | 1/3 | 1.33 | -300 |
| 66.67% | 1/2 | 1.50 | -200 |
| 55.56% | 4/5 | 1.80 | -125 |
| 50% | 1/1 | 2.00 | +100 |
| 45.45% | 6/5 | 2.20 | +120 |
| 40% | 3/2 | 2.50 | +150 |
| 33.33% | 2/1 | 3.00 | +200 |
| 13.33% | 13/2 | 7.50 | +650 |
| 5% | 19/1 | 20.00 | +1900 |
At most sportsbooks, American odds are the default. But how do American odds work? The favorite will carry negative odds (-), while the underdog will have a plus sign (+) next to their name.
American odds show how much a wager can win with a $100 bet. So, an NFL team carrying odds of +130 will be deemed the underdog, and if you return a successful bet, you would make $130 in profit off a $100 bet. The favorite may have odds of -120, so you would need to bet $120 to return a $100 profit.
Most of the reputable sportsbooks we work with will use moneyline odds based on wagers of $100, as it is a simple, round number.
With American lines odds, the (-) symbol preceding the odds suggests the team is the favorite, while the (+) symbol indicates that a team is the underdog. If you are bold and bet on the underdog at odds of +125, then a $100 wager would return $125 in profit.
With USA betting odds, the moneyline is the best way to describe how these odds work. The moneyline is a great starting point for novice bettors as they must predict who will win a match.
To use the NHL as an example, you could get the following odds on two teams for a regular season encounter:
Here, the Lightning are the short favorites, so if you backed the Buffalo Sabres with a $100 wager, and they won, you would make $145 in profit.
The moneyline is easy to understand as there are usually only two outcomes: a home win or an away win. The draw is negated, as most leagues go into overtime to decide a winner. American lines odds are easy for those who want to know how to read betting lines.
The point spread helps distinguish the quality in a matchup. So, if you were betting on the NBA, and the Los Angeles Lakers were facing Oklahoma City Thunder, the Lakers would be favorites. The point spread line might look like this:
With a point spread, both teams can be wagered on at -110 and that is a common line set by reputable sportsbooks. So, if you bet on either team, a $110 ticket brings $100 in profit.
Many of the top sportsbooks have a bet calculator installed that will show you what you stand to win. This will show how many units you need to bet to win 100 units. A minus symbol will denote the favorite, while the underdog will have a plus sign.
Here is how you calculate implied probability for American odds. Using our NBA example, we can calculate the chances of the Thunder beating the Lakers at odds of +500:
Implied Probability =100/ (positive American odds +100) x100%
Implied Probability =100 / (550 + 100) x100% = 100/650 x 100 = 15.38%
Also known as British odds, fractional odds are quite simple to calculate. If you bet $10 on a team with a price of 5/1, then a $10 winning wager would pay out $50. Some of our sportsbooks use fractional odds.
To understand sports betting odds, it’s important to work out how fractional odds work in practise. To use a soccer example, if you bet on a tie between Juventus and AC Milan in Serie A, you could work out the implied probability of a tie with odds of 3/1 as follows:
Implied Probability = [Denominator / (Denominator + Numerator) ] x100%
Implied Probability = [1/ (1+3) x 100% = 1/4 x100% = 25%
The bookmakers would indicate that a tie was unlikely.
For those eager to interpret betting lines, fractional odds are a great starting point. Although American odds are a default option at most of the operators we work with, fractional odds have become increasingly common. This is the case when it comes to betting on tennis and the totals over/under market.
So, for example, imagine you were betting on a men’s Wimbledon quarter-final tie between Rafael Nadal and Daniil Medvedev. You could bet that the match would go beyond 4.5 sets, so if it was a five-set thriller and the odds were 2/1, then your $10 bet would provide you with $20 in return.
If you can read sports betting odds in fractional, you’ll be able to play with confidence at betting sites.
There is a simple formula for converting fractions into implied probability. If you wanted to calculate the implied probability of Barcelona to win La Liga at the end of the 2022/23 season with odds of 2/1, it would be as follows:
Implied Probability = [Denominator / (Denominator + Numerator) ] x100%
1/ (1+2) x 100 = 33.3%
In this case, the bookies aren’t too confident in Barca lifting the title.
Also referred to as European odds, decimal odds are common at US sportsbooks. The ones we work with will generally list decimal as the second most popular option after American odds.
Decimal odds and working implied probability are the easiest to calculate. It may be easier to calculate potential payouts compared to fractional betting. If you wish to interpret sports betting odds, decimals will give you plenty of insight.
For example, if you backed the Green Bay Packers to lift the Super Bowl title next season with odds of 10/3, this would roughly equate to 3/1, which translates to 4.0 in decimal odds. By wagering just $1 on this selection, you would get $4.33 in return if you won your bet.
Decimals are a great introduction for those wishing to read sports odds, but you need to understand the math behind it. For example, if you were looking at golf markets and wanted to bet $100 on Scottie Scheffler to win The Open in 2023 with odds of 3.70, you simply multiply your stake by the odds served up, so this would equate to $370 (100×3.70) and this would represent a profit of $270.
If soccer is more your thing, then you could bet on Tottenham to beat Chelsea at Stamford Bridge, which might carry odds of 9.90, which would equate to $990 if you bet $100, yielding an $890 profit.
The implied probability ratio is easy to work out. If we use the above example of Tottenham to beat Chelsea at Stamford Bridge in a Premier League game with odds of 9.90, then you would calculate the implied probability as such:
Implied Probability = [Denominator / (Denominator + Numerator) ] x100%
1/9.90 x 100% = 10.1%
So, the bookmaker would rate Tottenham’s chances of victory over Chelsea as very slim.
It’s time now to answer some FAQs and tie up any loose ends for those who want to know how to read sports odds.
To convert odds to implied probability, use the following formula:
Implied Probability = [Denominator / (Denominator + Numerator) ] x100%.
This determines the chances of an event happening. So, odds of 2/1 will equate to 3.00 in decimal odds, which in turn, yield a 33.3% chance of an outcome happening.
In American odds, the minus symbol denotes the favorite, whereas the plus sign indicates the underdog.
5 to 2 odds are fractional and it equates to 2/1, as you divide the two numbers. If we translate this to implied probability, it would result in a 28.6% chance of an event occurring.
-110 would suggest that a team is trading as favorites to win a match. American odds are based on wagers worth $100. Here, a $110 wager would bring you $100 in profit.
