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How to calculate odds

While people who make money off betting may seem to be in possession of some higher knowledge, the truth is that betting is simple enough. Once you know how to calculate odds and how to compare bookmakers, you’re some way down the road to what the moneymakers do already. From this point, it’s a question of leveraging your own knowledge and learning from your mistakes – and you will make mistakes.

However, the sooner you start the learning process the better; so, in this article, we’re going to learn about calculating odds, and how to decide when to place money (as well as how much).

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Things you have to know when learning how to calculate odds

The first thing you need to know about betting odds is that they’re basically simple maths. In fact, most bookmakers and betting apps now provide their odds as “Decimal” numbers, which makes calculating odds simpler than it has ever been before; some bettors prefer to use the more traditional “Fractional” odds, as this is what they are used to. It’s worth knowing how to work with both, as you’ll see them in the process of learning the ropes. Here’s a quick guide to reading betting odds.

Being able to calculate odds will help you compare different bookmakers for the odds they offer on the same market. So, for example, if one bookmaker is offering “longer” odds for a bet you’re thinking of making than their competitors, it’s with the longer odds that you want to go. Once you know how to calculate odds, working this out becomes straightforward – and being able to work out your potential winnings at a glance will speed up the learning process.

How to calculate odds in betting: Decimal and fractional

Fractional odds

Knowing the likelihood of a certain result is something that’s not unique to experienced bettors – many people who’ve never placed a bet can tell you the chances out of 10 that, say, Barcelona will beat Juventus. How are odds calculated in football? Bookmakers do exactly the same as us – they weigh up probabilities and make an educated prediction.

Betting odds are relatively simple to understand when you know the principles behind them. You’ll see decimal odds expressed as a decimal number – for example, 2.50 – and the higher the number the more money you stand a chance to win; higher numbers represent longer odds, which is another way of saying that the outcome you are betting on is less likely to happen.

Fractional odds, for their part, are expressed as fractions – such as 5/1. The most important number is the numerator (the figure before the “/” sign) because, as with decimal odds, the higher it is the more money you could win. The denominator (the number after the “/”) will usually be a 1, but not always. The lower it is, the better, as it represents the amount you need to bet to win the amount expressed as the numerator.

That last point reflects the other important factor in calculating odds – how much you win depends on the amount that you are prepared to bet. The more you are prepared to bet on an outcome, the more your potential return from that bet. It’s an example of the risk/reward balance; the more you are prepared to risk, the higher your reward may be.

We’ll give a more practical rundown of how odds work in a moment, so you can see these principles in action, but for now, given the above, you can see that decimal odds are simpler to calculate. For beginners, they will usually be the odds they choose to go with (don’t worry, any online bookmaker will offer the option to pick how your odds are displayed, but the default is usually decimal).

How it works: Decimal odds in a practical test

If you are looking to place a bet on a football tournament – let’s take the World Cup as an example –  then your bookmaker will have odds available to help you decide whether to place that bet. They will be displayed, as mentioned above, in the form of a decimal number so, for example, you may see “Brazil 6.00, Germany 6.00, France 6.50”. This means that Brazil and Germany are equally likely to win, in the eyes of the bookmakers. France are a little less likely, but still have a good chance. Meanwhile, Nigeria are listed as “251.00”; they’re distant outsiders.

  • If you place a bet of £1 on France, and they win, you will win £6.50.
  • If that bet is £2, you would win £13.
  • If you placed that £2 on Nigeria, and they won, then your winnings would be £502.
  • You calculate winnings by multiplying your stake (the amount you put on the outcome) by the odds offered for the team to win.
  • Knowing how to calculate odds ratio in this way will help you judge whether your bet is one worth making. It’s even easier in practice, as online bookies will calculate odds and winnings for you when you place your bet, so there’s no need to do the maths yourself.

One thing to remember about decimal odds is that they include your stake in the price, so your £6.50 won on France includes the £1 you placed.

Other options to decimal odds


Fractional odds are the traditional way to calculate odds probability; although you’re more likely to see decimal odds the first time you bet, you’re more likely to hear people talk about — for example — “Leicester City’s remarkable 5,000/1 league win”. While decimal odds have the advantage of simplicity, fractional odds are more familiar; and they aren’t impossible to calculate, either. As an example, let’s compare the decimal odds in the above example to their fractional equivalent.

The same bookmaker offering odds for the World Cup, in fractional, would list Brazil and Germany as 5/1 and France as 11/2. Nigeria, as outsiders, would be 250/1. You may have noticed that the numbers in these examples, aside from being fractions, are different from the decimal ones. This is because your stake is only considered lost if your bet loses; with decimal odds, as you’ll remember, it’s counted in your winnings. A £2 bet on France would win you £11, but you’d also get your £2 stake back – so it’s exactly the same as if you bet with decimal probability odds.

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Why it’s important to know how to calculate odds in betting

It’s important to be able to calculate these odds for yourself, because they let you see at a glance which bookmaker to place your bet with. If you’re looking at two or more potential bookmakers, you want to go with the one who will offer you the best possible return on the bet you place. Sometimes, this will mean checking out an online odds comparison site, or you may read about the odds offline in an article.

In the former case, when checking online, the odds are likely to be listed as decimal, whereas offline fractional is still more usual. If you have seen both decimal and fractional odds quoted and are not sure how to calculate odds of winning, you could end up losing out on a better value bet. If you’re comparing between two different bookmakers who offer fractional – for example, you’re in a city centre and want to pick a betting shop to place your wager – it’s also important to know how to calculate betting odds. You always want to be able to maximise your winnings. If you don’t know how to calculate odds winnings to the value of hundreds can easily be lost.

A sound principle to work by is that if you’re researching the odds by going to bookmakers’ sites for yourself, stick to decimal as much as possible. That said, if you want to be able to maximise your chances of making money from betting, you should make the effort to learn fractional so as to have all bases covered. For an easy option, use a betting odds calculator to help you work out how much you can win.

Possible options

The importance of simplicity is obvious to the novice bettor – while more experienced punters can talk about Asian Handicap and Trixie betting like true natives, you’ll need a gentler introduction to calculating odds and placing bets. Some of the best bookmakers for rookies to try their luck are as follows.

Option 1: Grosvenor Sports

Particularly popular with football fans, Grosvenor Sports started out as an online casino operator and are most popular for their generous bonus structure. As an insight into these bonuses, ask yourself how are odds calculated in sports? Well, in Grosvenor’s case, when you sign up they’ll calculate those odds and then double them for your initial bet – meaning you can turn a promising 10/1 bet into a very attractive 20/1. That’s incredible value and potentially very lucrative.

Their site is also highly mobile-responsive and user-friendly; wherever you happen to be, as long as you can get an internet connection you can take advantage of any promising tips you happen to hear or read about. It even lets you carry out your own research, by providing a handy stats rundown on teams, results and – if you’re looking to bet on a specific match – info on the previous meetings between the teams or players involved.

Option 2: Betway

Betway have steadily gained a reputation over more than a decade as one of the most customer-friendly sites for sports betting. Much of this is down to their extremely responsive customer services which are accessible 24 hours a day in a number of languages. They’re also highly popular because their website is extremely easy to use. They know how to calculate betting odds, with prices that aren’t wildly generous nor excessively short, and with their regular Enhanced Odds promotions, you can find some excellent value.

Among other advantages for bettors using Betway, they offer a very wide range of events to bet on – they are among the market leaders in this respect – though a rare drawback is that they don’t have a live streaming service as some others do. This means you’ll need to find another way of following an event once you have money on it, though their in-play options do mean that if you want to cash out early it’s very easy to do so.

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Calculating odds a key attribute for any bettor

Being able to calculate betting odds and compare them at a glance – including on those occasions when you see them in different forms – will make you a more intuitive bettor who can find the value in markets wherever you see them. Although it can seem like an information overload at first, once you’ve run through it a few times you’ll find it’s pretty much second nature to perform the maths in your head.

When you put an ability to calculate odds together with an instinctive knowledge of sport, you’ve got two of the most powerful tools a bettor could want – and a pathway to greater enjoyment.