How to Read and Calculate Sports Odds

Learn how to read and understand decimal & fractional sports odds like a pro.

Whether you have a preference for horse racing, football, NLB, NFL, NBA or another type of sport, if you want to bet like a pro, you’ll need to know how to read sports odds.

Putting a bet on might seem simple in theory. Still, suppose you also understand the different types of odds that bookmakers and online betting sites use. In that case, you’ll be able to make more informed decisions and correctly calculate the returns that you potentially stand to win.

Odds can be displayed in various formats, and the three most common are decimal, American, and fractional.

This article acts as a guide to understanding and reading odds, and once you’ve had the chance to digest the information and practice a few calculations, you’ll be one step closer to betting smarter!


Understanding Decimal, American and Fractional Odds

Despite using different formats, decimal, American, and fractional odds all serve the same purpose.

They show:-

a) how much money you can potentially win by placing the bet and 

b) the likelihood of the outcome of the bet.

However, odds only give an indication of the probability of an outcome or event occurring. You should also bear in mind that other factors can influence the outcome. Such as injuries, cancellations, and weather/pitch/course conditions.

Bookies also need to make a profit and, therefore, they may slightly manipulate the odds by applying a margin. This built-in profit margin is often referred to as the “vig”, and it affects the real probability and the real odds.

For example, if a bookmaker calculates the probability of an event occurring as 2/1, they then deduct their margin (e.g. 5%), which would mean that the real odds offered are 19/10.

The above example uses the fractional odds format. When Using the same example in the American format, the real probability would be 300, and the real odds would be 190.

While using the digital format, the real probability would be 3.0, and the real odds would be 2.90.

How Do Decimal Odds Work?

You can tell if you’re looking at decimal odds as they’ll have a decimal point in them.

It’s relatively easy to calculate potential payouts when working with decimal odds as you merely need to multiply your bet by the odds for the team/event/horse that you’re betting on. You then need to minus the amount that you intend to bet from the payout.

To calculate the implied probability.

Here’s an example to show you how to view implied probability using decimal odds where the odds offered are 3.40:

1 ÷ 3.40 = 0.294 = 29%

How Do American Odds Work?

American betting odds are presented as three-digital numbers using + and – symbols.

They aim to show you which team, player or horse is the favourite and which is the underdog.

Favourites are indicated by the negative number, which tells you how much you’d need to stake to win $100. While underdogs are indicated by the positive number, which also shows how much you would win if you wagered $100.

In a scenario where Team A offers odds of -130 and Team B offers odds of +110, you would need to stake $130 on the favourite (Team A) to win $100 or $100 on the underdog (Team B) to win $110.

How Do Fractional Odds Work?

If you live in the UK, fractional odds are the most common type of odds that you’ll encounter at online and land-based sports betting brands.

They look like 9/4 or 1/2 and are pronounced 9 to 4 or 1 to 2 accordingly.

The figure on the left represents the number of times the bookie thinks the outcome will not occur. While the figure on the right shows how many times they believe it WILL occur.

Translating fractional odds into percentages is easy. You simply divide the number of expected successful outcomes by the total number of outcomes. So, using 9/4 as an example, you would divide 9 by 13 to give 69%.

Finding the Best Odds

MobiBet can help you find the most favourable odds from major online bookmakers and betting apps, and you can even use our odds calculator to work out how much you could potentially win with your bet.

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