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Fractional Odds Explained

Originally used in horse racing, fractional odds are one of the oldest forms of odds for sports gamblers. If you were to walk down London’s high street of bookmakers, you would see fractional odds adorning the walls of some the largest bookies in the world.

Keep reading to learn how to calculate and convert fractional odds.

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How to Calculate Fractional Odds

Fractional odds

Fractional odds, also known as UK odds, are most often used in the United Kingdom and Ireland. They are extremely simple to calculate because well, they are given in fraction form. The denominator (second number to the right) is the amount bet and the numerator (first number on the left) is the amount you stand to win.

Let’s say you bet on Liverpool to beat Newcastle United at fractional odds of 10/15.

For every $150 bet, your potential net profit would be $100. If you win, your original stake is also returned to you, leaving you with $250 ($150 stake + $100 profit) and a net of result of plus $100.

  • Liverpool to win (10/15): $150 to win $100 = $250 return

Let’s look at betting on an underdog or high odds bet, where the odds are more in your favor. Say you join a new betting site and bet on Newcastle United, the underdog at fractional odds of 5/1.

If you were to bet $100, your potential return would be $600 ($100 stake + $500 profit).

  • Newcastle United to win (5/1): $100 to win $500 = $600 return

When betting on an event in which there is a definitive favourite and underdog, the odds of the favourite are often referred to as ‘odds on’ and the odds of the underdog as ‘odds against’. If a bet is even money, the odds are not 1:1 due to the bookmaker’s juice or commission. In most cases, the odds will be 10/11, where the bettor risks $110 to win $100.

Fractional odds can also be attached to a point spread:

  • New York Giants -7 (10/11)
  • Philadelphia Eagles +7 (10/11)

The juice or commission on each bet here is fractional odds of 10/11, so you would need to bet $110 to win $100.

Fractional odds on chalkboard

Converting Fractional Odds to Decimal Odds

An easy way to convert fractional odds to decimal odds is to convert the fraction into decimal form and then add a 1.

For example, 5/1 in fractional odds would be 6.00 in decimal odds.

  • 5 / 1 = 5 + 1 = 6.00

Here is a conversion when you are betting on a large favorite:

  • 1 / 5 = 0.2 + 1 = 1.2

Final Thoughts on Fractional Odds

Understanding fractional odds is especially important to UK bettors, but even those not normally using these odds can benefit from understanding them.

Used by the world’s largest bookmakers, there is no doubt fractional odds are one of the preferred odds for sports bettors across the world.

About the author

Alan Penny


Alan hails from Northern Ireland and is an avid fan of all sports. He has been with us since 2017 and serves as SBO’s Editor-in-Chief. Alan passionately covers everything from the latest regulatory developments across the globe to tips on the latest football matches.

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