If you’re gambling on sports, then you must understand the maths behind betting odds. Odds will give you an idea of your chances of winning a certain bet (although, as you’ll see soon, it isn’t always an accurate reflection), plus let you know how much you could potentially win from a bet you’re planning to make.

We will be tackling this from the perspective of a British/Irish person since the way we display odds on these fair islands is slightly different from Europe, the United States, and elsewhere. However, don’t worry, we’ll still give you a quick overview of how those odds work too.

There are Multiple Ways Odds Can Be Displayed

As we said, there are multiple ways that betting odds can be displayed. If you head to AskGamblers UK, then you can see the various odds display methods. There are three options. Most online bookmakers will let you choose from any one of the following:

–       Fractional Odds: this is the odds display system we’ll be discussing on this page. It is the default system used in the UK and Ireland (plus, a few Commonwealth countries). You’ll know you’re looking at fractional odds if you’re seeing literal fractions e.g. 2/1, 8/2, etc.

–       Decimal Odds: this is the odds system used throughout most of Europe. It is also often the default system for international betting sites. The decimal odds display how much you win for every unit of currency wagered. So, let’s say there are decimal odds of 3.00. This means that for every £1.00 wagered, there is the potential to win £3.00. Honestly, it is the easiest system to understand. It is baffling we don’t use it in the UK.

–          American Odds: Americans like to do things in their own way, and the American odds system is insanely complicated for those who have no clue how it works. With American odds, you’ll either see a – or a + before a number. If you see a -, then that particular bet is the favourite. If you see a +, then that particular bet is the underdog. Now, here is where things get confusing. If you’re betting on a favourite, then the number after is how much you would need to bet to win $100. So, if the odds were -120, then you’d need to bet $120, to win $100. On the other hand, if you were betting on the underdog, that is how much you would win if you gambled $100. So, if it is +150, then you’d win $150, plus your initial stake, on a $150 bet.

We will be focusing purely on fractional odds here for our British and Irish readers. 

How Betting Odds Are Calculated

Before we get into how you can read betting odds and do some maths of your own, we figured we would give you an overview of how betting odds are calculated. Although, we must stress this is a very quick overview. There is a lot of complicated maths happening behind the scenes, and things do differ slightly from online bookmaker to online bookmaker.

These factors go into calculating betting odds:

–       The likelihood of an event happening.

–       How many bets are placed on each side of the bet.

–       The profit the bookmaker wants to make on the market.

Now, a lot of people seem to think that odds are an accurate reflection of the likelihood of something happening. This is true, to an extent. However, it doesn’t quite tell the whole story. Bookmakers want to make money on all their open betting markets, and to make sure people come back for more. This means that they keep constant tabs on the number of bets placed on either side of the market. Their goal is to always make a profit when bets are settled, so the odds are constantly balanced to guarantee this. This means that if, for some baffling reason, people place a rather hefty bet on something very unlikely to happen, the odds can start to tip heavily in that direction, just because the online bookmaker doesn’t want to take the risk of losing out.

This is why betting odds are almost always constantly changing. Bookmakers are always looking to make money and trust us, they do.

How to Read Betting Odds

Once again, we’ll discuss only fractional betting odds here. We’ll look at two things:

–       How to read the betting odds to determine winnings.

–       How to determine the likelihood, as a percentage, of a bet winning.

The first part is easy. With fractional betting odds, you’ll have two numbers. The first number is how much you can win. The second number is how much you would need to bet to win that amount. So, for example, if you had betting odds of 8/3, then to win £8, you’d need to bet £3.00. If you bet £1.50, you’d win £4.00. Simple stuff.

For the second part, you’ll need to think back to your maths classes. This is quite easy. Just use this formula:

–          Add the two numbers together.

–          Divide the second number by the number in the first calculation.

–          Multiply by 100.

So, let’s take our 8/3 example. 

–          8 plus 3 is 11.

–          3 divided by 11 is 0.27.

–          Multiply by 100 is 27%.

This means there is a 27% chance of winning that bet.

Let’s try that with 2/1:

–          2 plus 1 is 3.

–          1 divided by 3 is 0.33.

–          Multiply by 100, you’ve got 33%.

It is simple. Once you’ve nailed these calculations (which is what smartphones are for), then you’ll find it easier to work out your chances of winning a bet.

Final Thoughts

There you have it. There’s not a lot to understand when it comes to the maths behind betting. You don’t need to know how betting sites calculate odds since they all do it in different ways. You just need to understand how to calculate your chances of winning. That’s simple. Just use the calculations we gave you on this page.