Understanding Probability In Betting

It’s all well and good placing a bet, but if you don’t understand probability and how to read odds then you’re already on to a loss.

It’s one of the most important things to understand in betting before you even begin to consider which betting apps to play with or markets to place your bets on. 

Below you’ll find all you need to know about betting probability including what it is and how to read various forms of odds.

What Is Probability?

We’ll start with probability and what it is. In a nutshell, the probability of an event or outcome of an event is how likely it is to happen.

I’m betting, the probability is essentially how likely a bookmaker believes an outcome is to occur.

In regular probability, there is usually a definite probability. For example, in the toss of a coin, the probability of it landing on heads or tails is 50/50.

However, in sports betting it isn’t that simple. For example, the probability of Arsenal beating Newcastle is much larger than vice versa. 

Therefore, when bookmakers are studying the probability of an event occurring it’s much more subjective.

Therefore they will take a range of details, including form, league position, injuries and suspensions and much more.

Probability In Betting: Calculating Odds

Betting is all about studying the probability of an event occurring and placing your bets in accordance.

You can calculate the probability of an event occurring via the odds being offered by a bookmaker.

As you’d probably expect, the shorter the odds on a market, the higher the probability according to the bookmaker. 

Reading The Odds

You can read the odds to calculate probability across both fractional and decimal odds as well as calculating your returns.

Below you’ll find how to calculate both fractional and decimal odds to help you understand probability…

Fractional Odds

Fractional odds are the most common type of odds found in the UK and can be calculated relatively easily. 

Let’s use an example to highlight how odds can be calculated. If you were to bet on a game with bet365 between West Ham and Manchester City in the Premier League. You’ll likely receive odds of:

West Ham: 10/1

Draw: 19/4

Manchester City: 1/4

You can use the numbers within the odds to calculate a bookmakers probability of the event occurring. The number on the right of the fraction represents the number of times an event will happen of the total sum of the numbers, while the number on the left represents the number of times it won’t happen of the total sum of the numbers.

In this instance then, the probability of Manchester City winning would be four times in five matches. In the case of West Ham it would be a one in 11 chance of them winning.

You can add this into a simple equation to discover the percentage chance an event has. The equation is as follows:

[Right hand number] / [Total of fraction] = Probability

For example, in the case of Manchester City it would be:

4 / 5 = 0.80

Therefore Manchester City would have an 80% chance of winning the game.

You can also calculate your winnings using fractional odds. To do so it’s best to think of fractional odds as A/B. For every value of B you bet you will receive A in return, plus your stake.

Therefore with Manchester City, for every £4 you were to bet you’d receive £1, plus your stake.

Decimal Odds

Calculating probability from decimal odds is just as simple and can be done using the following calculation:

Probability = 1 / Decimal Odds

Using the example above, the fractional odds converted into decimal would be:

West Ham: 11.00

Draw: 5.75

Manchester City: 1.25

If you wanted to then calculate the probability of Manchester City, you would then use this equation:

1 / 1.25 = 0.80

To calculate your winnings from decimal odds is just as easy. All you are required to do is multiply your stake by the decimal odds. For example, if you were to place £10 on Manchester City to win, you would use this equation:

10 * 1.25 = 12.5

In this case, you would receive a return of £12.50. When calculating your return with decimal odds this is inclusive of stake.