Betting Odds Explained


Difficulty: Easy Read time: 5 mins

Betting odds explained

Matched betting is available to everyone.

You don’t even need to have placed a bet before!

But before we get started, allow me to explain how betting odds work.

What are betting odds?

Betting odds are numbers used by bookmakers to represent the probability of an outcome occurring.

What is probability?

Before we can understand betting odds, it’s important to understand probability.

Probability is basically the likelihood of an outcome happening and is usually displayed as a percentage.

For example, if we were to toss a coin, there are two possible outcomes. There’s a 50% chance that the coin will land on heads and a 50% chance that the coin will land on tails.

How do betting odds work?

Betting odds tell us how much we stand to win if our bet is successful.

They can be displayed as fractions or decimals.

Traditionally, bookmakers display their odds as fractions, such as 9/1 on England to win the World Cup.

Fractional Odds Example

Fractional odds explained

Fractional odds tell us how much we stand to win in relation to our stake.

The number on the left side of the fraction is the amount we stand to win if we stake the amount on the right side of the fraction.

So, if we bet £1.00 on England to win the World Cup at odds of 9/1, we’ll win £9.00, plus our £1.00 stake back, giving us total returns of £10.00.

Here are some other examples…

5/1 – We’ll win £5.00 for every £1.00 we bet
6/4 – We’ll win £6.00 for every £4.00 we bet
1/2 – We’ll win £1.00 for every £2.00 we bet

Decimal odds explained

Decimal odds show us how much a winning bet will return, inclusive of our stake.

We simply multiply our stake by the odds, to get our total returns.

So, if we bet £1.00 on England to win the World Cup at odds of 10.00, we’ll win £10.00, which includes our £1.00 stake.

Here are some other examples…

6.00 – A £1.00 bet would return £6.00
2.50 – A £4.00 bet would return £10.00
1.50 – A £2.00 bet would return £3.00

Fractional and Decimal Odds Comparison

As you can see, the fractional and decimal odds equal the same; they’re just different ways of displaying things.

Which odds should we use for matched betting?

When it comes to matched betting, we need to use decimal odds.

That’s because decimal odds are simpler and much easier to compare at a glance, which is an essential part of the matched betting process.

The betting exchanges display their odds as decimals, so it makes sense to use decimals at the bookmakers too.

To illustrate just how much easier decimal odds are to compare than fractions, take a look at the following graphics…

Which Fractional Odds Are Bigger?

Which Decimal Odds Are Bigger?

As you can see, it’s much easier to compare decimal odds at a glance than it is fractional odds.

That’s the basics covered, but feel free to keep reading for some advice on converting odds and a bit more about probability.

Converting fractional odds to decimal odds

We shouldn’t need to convert odds manually all too often as we can simply change our odds preference at the bookmakers.

After a while, you’ll probably find yourself converting odds in your head without even thinking.

Here’s how it’s done…

So, if we want to convert 9/1 into decimal odds, we would simply divide the number on the left side of the fraction by the amount on the right side of the fraction and add one, to account for our stake.

9 ÷ 1 = 9…
…9 + 1 = 10.00 (Decimal odds)

Here are some other examples…

5/1 – 5 divided by 1 equals 5, plus 1 which equals 6.00
6/4 – 6 divided by 4 equals 1.5, plus 1 which equals 2.50
1/2 – 1 divided by 2 equals 0.5, plus 1 which equals 1.50

Calculating probability from betting odds

We can use betting odds to calculate the implied probability of an outcome occurring.

To calculate probability from fractional odds, we simply divide the number on the right side of the fraction by the sum of both numbers.

So, if the odds are 9/1…

9 + 1 = 10…
…1 ÷ 10 = 0.10 (10% chance of the outcome occurring)

Here are some other examples…

5/1 – 1 divided by 6 equals 0.167 (16.7%)
6/4 – 4 divided by 10 equals 0.40 (40%)
1/2 – 2 divided by 3 equals 0.667 (66.7%)

To calculate probability from decimal odds, we simply divide the number one by the decimal odds.

So, if the odds are 10.00…

1 ÷ 10.00 = 0.10 (10% chance of the outcome occurring)

Here are some other examples…

6.00 – 1 divided by 6.00 equals 0.167 (16.7%)
2.50 – 1 divided by 2.50 equals 0.40 (40%)
1.50 – 1 divided by 1.50 equals 0.667 (66.7%)

Hopefully you will now have an understanding of how betting odds work and why we use decimal odds when placing our matched bets.

If things are still a little unclear, don’t worry. Things should become clearer as you move on.

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