Online Betting » Betting Guide » Explaining Fractional Odds: What Are Fractional Odds in Betting and How Do They Work?

Explaining Fractional Odds: What Are Fractional Odds in Betting and How Do They Work?

Dave Kuzio
Fact checked by: Jim Knight
Publish Date: 01.07.2024

Understanding how all the key betting odds work is crucial if you want to understand exactly what you are betting on. Fractional odds, decimal odds and American odds are the three main systems used throughout the world.

Fractional odds are predominantly used in the United Kingdom and Ireland and are seen as a simpler way to understand how your bet works. This guide will explain fully what fractional odds are, how they differ from others and how to calculate them.

What Are Fractional Odds

Fractional odds are sometimes described as UK odds because that is their preferred way of displaying prices in the United Kingdom and Ireland.

The fractions indicate the probability of something happening in your chosen sport. The first number is how much money you will win against the amount you bet as the second number. Fractional odds are always numbers with a slash separating them.

  • For example, 5/1 will see you win £5 for every £1 you stake as well as your original stake returned.
  • 5/4 will see you win £5 for every £4 you stake.

How To Understand Fractional Odds

Fractional odds tell us two things about your bet. The price and the probability of that happening.

A lot of people find fractional odds the easiest to understand. If you are a beginner then you might take a short period of time understanding the ins and outs when it comes to a bet ending in 3 or 4, but once you do it should be easy to follow.

Here is a brief look at how the fractional odds work and what profit you would make using this system.

2/7£10£2.90 profit + £10 stake
4/5£10£8.00 profit + £10 stake
7/4£10£17.50 profit + £10 stake
6/1£10£60 profit + £10 stake
25/1£10£250 profit + £10 stake
125/1£10£1250 profit + £10 stake

The Probability of Fractional Odds Betting

As with any style of odds – fractional, decimal or American – you can work out the probability of that bet being successful with a simple formula.

The best explanation for calculating the probability of fractional odds would be to substitute the number in the odds for letters. In this instance, 6/1 becomes A/B. The calculation would then be – Probability (%) = B/(A+B).

Fractional Odds Probability

Fractional Odds% =B/(A+B)AnswerProbability
2/77/(2+7) =0.777877.78%
1/11/(1+1) =0.550%
6/11/(6+1) =0.142814.29%
9/11/(9+1) =0.1010%
90/11/(90+1) =0.011.10%

How To Convert Fractional Odds to Decimal And American Odds

Fractional odds are straightforward to understand, but you might prefer to use a different method. There is no right or wrong answer when it comes to choosing your betting odds. I prefer fractional odds, while others find decimal or American more appealing. At the end of the day, you have to use whatever makes you comfortable and allows you to understand the odds clearer.

Here I am going to explain in simple terms how you can convert your fractional odds so that you can understand them in decimal or for the American betting markets.

Below you will see the formulas used and an example of how to convert your fractional odds into decimal or American odds:

Convert To Decimal Odds

There are different ways to convert your fractional odds to decimal or American. Yes, it would be easy to use an odds converter tool that you can find online, but sometimes you can get a sense of wellbeing by doing it the old fashioned way – working it out on your own.

The easiest formula you can use to convert to decimal from fractional odds is to divide the first figure of your fraction by the second figure and then simply add one and you will get your odds in decimal form.

If you were backing a team to win a soccer match at 11/5, you would divide 11 by 5 and then add one.

  • For example, 11/5 =2.20 + 1.00 = 3.20

Convert to American Odds

When you are converting fractional odds to American odds, just like with decimal odds there are two ways of doing it due to the positive and negative markets. Odds on selections are odds like 4/5 or 5/6 where the second number is larger than the first one. Odds against sees the first number larger than the second number.

Converting fractional odds to American odds is a little complicated, but it will not take you long to fully understand them.

For an odds-on bet, you will need to divide the two fraction numbers before multiplying by 100 and then divide that number by 100 to get your American odds.

  • Example, Odds 4/5 – 4/5 x 100 = 80; 100/80 = 1.25  – -1.25 is the American odds version of 4/5

For odds-against, you will need to divide the two fraction numbers again and multiply by 100.

  • Example, Odds -11/8 – 11/8 = 137.5 – +137.5 is your American odds.

Fractional Odds Pros And Cons 

  • Popular in UK
  • Easy to understand
  • Clear payout
  • Confusing if not from the UK

Final Say On Fractional Odds

Choosing which method of betting odds you have displayed on your betting spot is personal preference. It is as simple as that.

In the years that I have been betting, I have always used the fraction method. I find it helps me understand the bet and odds more so I know what I could potentially win.

If you feel you are still a novice when it comes to fractional odds, continue to learn about them and make sure you fully understand them. They are a fundamental part of sports betting and once you master how they work it will make your betting journey easier to navigate.

Having a working knowledge of how fractional odds work can only benefit you in the long run.

Fractional Odds FAQ

🔢 Why Should I Use Fractional Odds?

You do not have to exclusively use fractional odds in your betting slips. There are three separate options, and you use the one that suits you.

🇬🇧 What Countries Use Fractional Odds?

The United Kingdom and Ireland are the only ones that use fractional odds as a constant.

❓ Can I Change My Betting Odds Method?

Most UK bookmakers will automatically display fractional odds. It is the most used method and is very popular. If you want to use decimal or American odds, then you can easily change the format in your account settings. Once you save the settings, your preferred betting odds will display when you log back in.

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