There are a number of ways that odds can be read, from fractional, to decimal to American. Translating them from one format to another can be a tricky process which is why we at Compare.bet have built an odds converter that lets you convert the price of a wager instantly – it even tells you the implied probability! Try it out below.
Different Types of Odds Explained
The various odds formats are designed to tell you something different about the price of a bet. Let’s take a closer look at the differences between each odds type.
Fractional odds are traditionally most common at UK betting sites, but you’ll find them at the UK’s newest bookies too. With fractional odds, the numerator tells you how much you’ll win when you place a bet equal to the value of the denominator. The numerator reflects the net profit, so a £10 bet with odds 2/1 will see you win £20 profit.
Equally, if you place a wager where the numerator is smaller than the denominator, such as 1/5, then you will win £1 for every £5 you place.
Decimal odds now rival fractional odds as the most popular format and are the default format in most of Europe, Australia and Canada because of their simplicity. To calculate your potential winnings, you simply multiply your stake by the decimal odds.
The decimal odds reflect your total returns, meaning both your profit and original stake. So if you win a £10 bet with 2.5 odds, you’ll get £25 back – your £10 stake plus £15 profit.
As the name suggests, these odds are used at US sportsbooks. With American odds, positive odds tell you how much you’ll win from placing a £100 wager, while negative odds show you how much you need to wager to win £100.
American odds reflect your net profit, so a £10 bet on +130 odds would net you £23 – £13 profit. A £10 bet on -160 odds would win you £6.25 profit.
Each Way Betting Calculator
As well as a dedicated odds converter, we at Compare.bet have also built an each way betting calculator. Each way bets are commonly found on horse racing markets, but can also be used on selected golf tournaments.
An each-way bet is a wager on two separate outcomes: to win and to place. If your bet wins, then you collect a payout on both your wager winning and placing. But if your bet places, then you only collect the payout part of your bet. By covering multiple outcomes, an each-way bet is, therefore, something of an insurance wager.
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How it works
The Maths Behind the Odds Converter
Odds conversion calculations vary depending on the odds formats in question. Luckily, our odds converter does the hard work for you, so you don’t need to get your calculator out. However, if you’re interested in how the odds converter works, here’s a look at the maths behind it.
Fractional to Decimal Odds
To convert fractional odds to decimal odds, you need to turn the fraction into decimal form and then add 1. To convert a fraction to a decimal, you simply divide the numerator (the number left of the divider) by the denominator (the number right of the divider).
Let’s say you want to convert fractional odds of 1/5 into decimal format. To do this, you’d do the following :
1/5 = 0.2
0.2 + 1 = 1.2
To convert decimal odds to fractional odds, you need to do the reverse. This means positioning the decimal number as the numerator and 1 as the denominator. You then multiply the top and bottom numbers by ten until there are no decimal places left.
For example, to convert odds of 1.4, you do the following:
1.4 – 1 = 0.4
(0.4/1) x 10 = 4/10
You then simplify the fraction by dividing both numbers by the largest common denominator. In this case, the largest common denominator is 2, so the fractional odds you’re left with are 2/5.
Fractional to American
The calculation for converting fractional odds to US odds differs depending on whether you’re converting odds over 1/1 (an underdog) or under 1/1 (a favourite). However, you’ll always need to convert the fraction into a decimal, dividing the numerator by the denominator.
For odds over 1/1, you then multiply the fraction by 100. So to convert odds 3/2, you’d carry out the following calculation:
3/2 = 1.5
1.5 x 100 = +160
If you want to convert odds on a favourite, such as 2/3, you first convert the fraction to a decimal and then divide -100 by the decimal. The calculation for this is:
2/3 = 0.67
-100/0.67 = -150
So here you would divide -100 by 0.67 to give you -150.
Converting American odds to fractional odds requires the reverse calculations. For positive odds, this means multiplying the odds by 100, converting the answer to a fraction and then reducing the fraction to its simplest form. To convert negative US odds, you divide 100 by the odds, turn the decimal into a fraction and then reduce to its simplest form.
Decimal to American
The calculation for decimal to American odds also depends on whether you’re converting odds on an underdog or favourite. For decimal odds of 2.00 or greater, you simply minus 1 and multiply by 100. So for decimal odds of 3.00, you do this:
3 – 1 = 2
2 x 100 = +200
To convert odds of less than 2.00, you minus 1 from the decimal and then times the answer by -100. So the calculation for decimal odds of 1.50 is:
1.50 – 1 = 0.5
0.5 x -100 = -200
To convert American odds to decimals, you simply carry out the reverse calculations. So for positive odds, you divide by 100 and plus 1, and for negative US odds, you disregard the negative sign, divide by 100 and then add 1.
Betting sites don’t tend to display the implied probability of bets, but it is very useful for bettors to understand. The implied probability provides the simplest reflection of how likely a bookie believes a particular event is to happen. For example, an implied probability of 10% shows that a bookie believes there is around a 1 in 10 chance of that event occurring.
The calculation for converting odds to a percentage depends on the odds format. For fractional odds you use the following equation:
(Denominator / (denominator + numerator)) x 100 = implied probability
For decimal odds, the calculation is:
(1/decimal odds) x 100 = implied probability
And finally, to work out the implied probability from US odds you do the following:
(Negative odds / (negative odds + 100)) x 100 = implied probability
(100 / (positive odds + 100)) x 100 = implied probability
If you want to find out the implied probability of some of the most high-profile betting events around, then check out our historical odds trackers for markets such as Premier League Winner, NBA Winner and the 2022 Oscars below.
Common Conversions Between Different Odds Types
There are a variety of common wager prices available to punters that can be easily translated into various odds formats. Here are a few examples of converted odds to see how different types compare.
Convert Odds with Confidence
Now that you are familiar with the different odds formats and the work that goes into converting one to another, you should be ready to bet with confidence. Why not check out our list of top betting sites and sign up to your favourite to get started.
Frequently Asked Questions
How is probability calculated?
Working out the probability of an event, and therefore the odds of that event happening, is a very complex science. Bookmakers take into consideration a whole host of factors including the recent form of a team or individual, previous results between two opponents and the coaches pre-game comments, to name just a few. The best betting sites will also go into quite granular detail to price a bet, such as when and where on the pitch a football player has scored the most when setting the odds of the next goalscorer market, for example.
How can I calculate implied probability using sportsbook odds?
Sportsbook odds are simply a representation of how much you would be willing to lose and win when predicting if an event will happen. As such, they are not the same as the implied probability of an event, which is the overall likelihood of an event happening. In order to work out the implied probability from fractional odds, for example, you divide the denominator by the sum of the denominator and numerator and then multiply the result by 100.
What are the most common odds in the UK?
The odds most commonly used in the UK are fractional. The top number determines how much you win if you placed a wager equal to the bottom number. So, if you laid a £10 bet on odds of 7/1, you would win £70.
Can I convert odds on my chosen betting site?
Most betting sites in the UK provide players with the option to choose how they want to see the odds on display. This means you are free to flit between fractional, decimal and American odds as you wish.