Fractional Odds

By
• Learn The Lines
• May 17th, 2022

Fractional odds, sometimes known as British odds, UK odds or traditional odds are the most common odds type in the United Kingdom and Ireland. 

Our informative guide will educate you on fractional odds, explaining exactly how they work, how they can be read and the key differences between fractional odds, decimal odds and American odds. 

What are Fractional Odds?

Fractional odds are most popular with UK and Irish bookmakers. You will typically find fractional odds written with a slash (/) or in some cases a hyphen (-), for example 5/1 or 5-1 which would be said as “five-to-one”.

A fractional odds listing of 5/1 would mean for every $1 wagered you’d stand to make $5 profit, in addition to your $1 stake returned. So in total you would have $6 returned to you. So in other words the number listed to the left of the slash (/) is the amount you stand to win with every amount staked to the value of the number on the right of the slash (/). A $10 stake on the 5/1 odds would return $60 ($50 profit and your $10 stake returned).

In some instances you may see fractional odds like 11/10 or 11-10, so in that instance for every $10 staked you’d make $11 profit, or 6/4 with every $4 staked you’d make a $6 profit for example. 

How do Fractional Odds Work?

Fractional odds are fairly easy to read due to the fact that you know if you stake the amount listed on the right of the slash (/) that you stand to win the amount on the left of the slash (/) as pure profit on top of your returned stake value. 

The calculation to work out your fractional odds return would be as follows:

Stake x value on the left side of the fractional odds slash divided by the value on the right side = win amount.

So using the same example the calculation of a $10 bet at 5/1 odds would be as follows:

( 10 x 5 ) divided by 1 = 50 and you know that your stake is returned, so in total you would get back $60. 

Sometimes you might find a strong favorite who is odds on and they might have odds of say 1/5

which is an example of the value on the left side of the fractional slash being less than the right side. So in this instance the calculation would be the same but 10 x 1 divided by 5 which tells you for every $10 bet you would make $2 profit. 

Let’s take a look at some real life examples of fractional odds on an MLS soccer match:

It’s the Los Angeles Derby and LA Galaxy are facing rivals Los Angeles FC in an MLS League game. The moneyline odds at a well known sportsbook on the game are as follows:

LA Galaxy – 31/20

DRAW – 14/5 

Los Angeles FC – 31/20

As you can see both the LA Galaxy and LA FC have been allocated exactly the same fractional odds because they are judged to be of a similar ability. 

This is how each possible match result would be broken down from a $5 bet. 

A $5 winning bet on the LA Galaxy at 31/20 = $7.75 profit, with a total payout of $12.75 with your $5 stake returned to you. 

That’s because using the same calculation as before would bring the following: (5 stake x 31) divided by 20 = 7.75

A $5 winning bet on the DRAW at 14/5 = $14 profit. With a total payout of $19 (5 x 14) divided by 5 = 14.

And finally a $5 winning bet on LA FC at 31/20 = $7.75 profit, with a total payout of $12.75 with your $5 stake returned to you (5 stake x 31) divided by 20 = 7.75.

Now let’s take a look at a fractional odds example with a short priced favorite to crunch the numbers there. 

You might fancy a bet on the MLB game between the Boston Red Sox and the Baltimore Orioles. The moneyline fractional odds are as follows:

Boston Red Sox – 10/23

Baltimore Orioles – 19/10 

We can see that the Boston Red Soxs are the 10/23 favorite to win the contest because they are odds on, meaning the value to the right of the slash (/) is bigger than the value on the left. Whereas the Baltimore Orioles are 19/10 and we know they are the underdog of the contest because the value on the left of the fractional slash is higher than the value on the right. 

Red Sox are 10/23, the fractional odds are effectively telling us that for every $23 stake you will make $10 profit. That doesn’t mean you have to stake $23 though, you can stake however little or much as you like and the profit return will be calculated using the same calculation as above (stake x 10) divided by 23. So a $50 bet on the 10/23 would look like:

(50 stake x 10) divided by 23 = $21.74 profit

Converting Fractional Odds Into Probability Percentages 

Fractional odds can always be converted into percentages, which is extremely handy when wanting to know the odds implied probabilities. 

To convert your fractional odds into implied probability you follow this formula:

1 divided by (fractional odds + 1) x 100 to give the implied odds percentage value.

If we wanted to find the implied probability of 2/1 the calculation would be like this: 

(1 divided by (2+1) x 100 = 33.33 (33.33% implied probability)

Fractional Odds vs Decimal Odds & American Odds

You may see all three odds types listed at different sportsbooks depending on your location and your own personal preference. Some sportsbooks even allow you to opt for your preferred odds type and will then list their betting markets in that format. 

Let’s see how all three odds types would look with a $10 stake on an evens money bet:

A $10 bet with Fractional Odds would look like this: $10 at 1/1 fractional odds returns $20 ($10 profit and your $10 stake returned)

A $10 bet on the same odds in American Odds format would look like this: $10 bet at +100 returns $20 in total.

A $10 bet on the same odds in Decimal Odds format would look like this: $10 bet at 2.0 returns $20 in total.