How Fractional Odds Work

Fractional Odds Guide

Understanding how Fractional odds work & why they are different?

The odds displayed by bookmakers are primarily dependent on the region they’re located. Sportsbooks in the U.S. mainly use American odds; markets in Europe and other parts of the world prefer decimal odds, while in the UK, fractional (British) odds are the most common. 

As the name implies, fractional odds are written as fractions. Some people may think fractional odds are difficult to read and understand. 

They may not seem as simple as other types of odds but are easy to understand once players become accustomed to them. 

For those who plan on getting started betting in a casino, sportsbook, or any type of wagering, it’s critical to understand how all odds formats work. 

Understanding the Main Types of Betting Odds

Making smart wagers requires players to understand the main types of betting odds and know how to read and interpret the different formats.

The various ways of presenting the same odds don’t make a difference in the amount paid out if the bettor wins. This means the chances of a team winning can be presented and converted in any of the previously mentioned formats.  

How Fractional Odds Work

Fractional, or British odds, are popular at bookmakers in England and Ireland. The odds are written using a slash (/), as with writing a fractional number or hyphen (-). 

When bettors see the odds written in the form of a fraction, they should recognize them right away as fractional odds. 

How Fractional Odds Are Written

Fractional odds will always be written using whole numbers. So instead of bookmakers displaying odds as 3.5/1, it would be shown as 7/2.

For example, using fractional odds of 2/1, the number on the bottom, or to the right, represents the wager amount, while the top number represents the amount that bettors can win if the pick is correct. 

So in the example, one is the wager amount, while two represents the amount that can be won.  Simply put, on a wager of $10 using the above odds, the bettor would win $20. 

The number on the left is referred to as the numerator, and the number on the right is the denominator. When reading fractional odds, 2/1 would be read out loud as “2 to 1.”

Odds of 1/1 are called “even” since the amount wagered and the winning amount are of the same value.

Fractional Odds and Implied Probability

The percentage showing the chances of an event happening based on bookmakers’ odds is known as implied probability. 

An event with a high likelihood has a greater chance of happening, meaning a higher percentage translates to a higher probability. 

Conversely, an event with a low probability has a lower chance of occurring, meaning it will have a lower probability percentage. 

Placing an implied probability percentage to fractional odds is simple, with only one conversion formula required: Fractional odds implied probability = (1÷ ((Fractional odds) +1)) x 100.

Using the same example of 2 to 1 odds for a team to win, the implied probability would be (1÷((2/1) +1)) x100=33.3%. 

This means the selected team has a probability of 33% to win the event. Players should also remember that when adding the implied probability of two teams in the same event, the result will always be more than 100% because of the vig added by the bookmaker, which is the primary way they profit. 

Wholesale odds are known as the “real odds,” which is the 100% probability of an event with odds not including any vig. It can also be described as having the bookmakers’ “overround” built into the odds. 

This is because a wholesale odds index will display all prices without adding profit margins for the bookmakers listed.  

Other Types of Odds: How to Understand Them?

For anyone planning to take up sports betting, they must interpret and understand other types of betting odds. 

Players also need to be familiar with conversions between the different odds formats, converting odds to implied probabilities and know the difference between the actual chances of an event occurring as opposed to the odds displayed by the bookmakers. That’s when players will know that they’re placing a truly informed bet. 

1. European Odds

Also known as decimal or continental odds, this format is popular in Canada, Australia, New Zealand, and continental Europe. They are somewhat easier to understand than most formats, as the favorites and underdogs are immediately identified by looking at the numbers. 

In decimal odds, the number shown represents the amount a bettor will win for every $1 wagered. The number shown also represents the total payout rather than only the profit. 

What Does It Mean?

This means the amount staked is already included within the number, which makes it easier to calculate the total payout. 

For example, odds of 1.30 would indicate a payout of $120 on a $100 wager. Deducting $100 will show the total from this wager was $20. The higher the decimal odds, the less probable it will be for that pick to win. 

2. American Odds

American odds, also known as moneyline odds or U.S. odds, are used mainly in the United States. 

The odds for the favorite always have a minus (-) sign in front of the number and show the amount bettors must wager to win $100, while the number for the underdog will show a plus (+) sign and indicates the amount the bettor can win for every $100 wagered. 

On both sides of the odds, a winning wager would pay the initial stake back in addition to the amount of profit won. 

The Favorite Winning Increases

The difference between the favorite and underdog will widen as the probability of the favorite winning increases. 

For example, a team has odds of +200, meaning the probability of them winning is lower. If that team wins, the bettor gets back the initial wager of $100 in addition to the $200, making the total payout $300. 

A favorite team at -200 means the bettor needs to wager $200 to make a $100 profit. If that team wins, the bettor receives back the original $200 plus the $100 in profits and a total payout of $300. 

The Difference Between Fractional and Other Odds

Although the odds types look much different, their purpose remains the same. They all show bettors how much they can profit from each bet, which is consistent with every kind of odds used. Odds can be shown in any of the formats for all sports. 

Depending on the Target

However, it depends on where the sport’s target audience is located. For example, odds for NFL matchups will always be shown in American odds, even for offshore bookmakers, because the target betting market is primarily based in the U.S.

Most online sportsbooks will now let bettors change between American, fractional, and decimal odds on all sports markets. 

Converting American and Decimal Odds

However, converting American and decimal odds is a little more challenging because the moneyline is shown as both positive and negative numbers. 

All players need to do to convert positive American odds to decimal odds is to divide the moneyline by 100 and add 1. 

To convert negative American odds, players should divide 100 by the negative odds and then add 1. For example, odds of +240 divided by 100 is 2.40. Add 1 to the result to get the decimal odds equivalent, which is 3.40. 

Want to learn more about Fractional odds? Follow us on Twitter

Fractional Odds FAQs

Understanding how different odds work means that players can look for odds from betting sites worldwide that display their odds in only one format. It also helps bettors to be accurate and not make mistakes, such as putting a big wager on a game with bad odds.

Most bookmakers have handicappers who calculate odds based on various factors, such as where the game is played, the weather, and any player injuries that may be involved. 

Odds can change quickly as events happen in live betting. Bookmakers will also use odds from Las Vegas sportsbooks to gauge their own calculations, which may influence the odds offered to all players.

No. No matter which sport is being played, the odds can be shown in any of the three formats. If not, bettors should learn how to convert any odds to the preferred format to ensure they make the correct choice.

Bookmakers in the UK use the fractional odds format more than any other, while decimal odds seem more common throughout Europe. 

This could be because they are easier for players to calculate winnings. However, sportsbooks almost exclusively use American odds in the U.S.

Yes. Sports betting odds are constantly changing before the game takes place. In live betting scenarios, the odds will change during the event. 

Things that may influence the odds are public betting patterns, such as a lot more money placed on one team than the other. 

Sportsbooks will change the odds to even out the amount bet on each team, which is the goal of handicappers that set sports betting odds. 

Sports that may be less popular can have less favorable odds because less money is being wagered in that market.