How to Convert Odds

Convert odds

There are three basic steps to convert odds

1. Understand the odds format by answering the question: Are the odds you want to convert Decimal, Fractional or American?

2. Convert the odds to their implied probability.

3. Convert the implied probability to your preferred odds format.

For example, “Decimal Odds” of 3.00 has an implied probability of 33.3% which can then be converted to fractional odds of 2/1.

This article discusses this process of odds conversion in detail with the use of step by step real world examples. If you’re completely new to betting odds and implied probability, the article below presents a great introduction and overview.


How To Convert Odds To Implied Probability

Typically, there are three kinds of odds you will come across in the sports betting landscape.

  • “Decimal Odds”: represented as 1.65 or 2.95 etc.
  • Fractional odds: represented as 5/2 or 3 to 2 ‘on’ etc.
  • Moneyline odds: represented as -120 or +140 etc.

They all reflect the same thing, the return you will receive on a given amount of money placed on a bet. To convert your odds to implied probabilities or an implied probability to odds, you can either use our odds conversion calculator or do it by hand with the formulas provided below the calculator.

Converting “Decimal Odds”

“Decimal Odds” are a simple reflection of the return you will receive for each single unit placed. For example, let’s say bookmaker Matchbook is offering odds of 1.65 for Manchester United to win. This means that for every 1.00 you bet on that particular outcome, you will receive a profit of 0.65 should Manchester United win.

To convert these odds to their respective implied probabilities we make a simple calculation.

Converting “Decimal Odds” to implied probability formula:

Implied probability = 1 / “Decimal Odds”

Let’s look at an example, in which Diego Costa to get a yellow card is odds 1.65.

Example: How to convert “Decimal Odds” to its implied probability

1 / 1.65 = 0.606 = 60.6%

Multiplied then by 100 to express as an implied probability percentage of 60.6%.


Converting Fractional odds

Fractional odds are generally the most traditional form of expressing betting odds. They are a simple reflection of the return you will receive for a particular amount bet.

So for example, let’s say bookmaker Deltin is offering odds of 5/2 for a particular horse to win an upcoming race. The odds of 5/2 (expressed as “5 to 2”) means that for every 2 units that you bet, you will receive 5 back as profit. So if you bet €200 on that horse, you would have received €500 profit in return plus your original stake of €200.

Converting fractional odds into implied probability formula:

Implied probability = denominator / (denominator + numerator)

Let’s look at an example, in which Diego Costa to get a yellow card is odds 5/2.

Example: How to convert fractional odds to its implied probability

5 / 2 = 2 / (2 + 5) = 2 / 7 = 0.2857 = 28.57%

Multiplied then by 100 to express as a implied probability percentage of 28.57%


Converting Moneyline Odds

Moneyline odds, also known as ‘American odds’ are probably the most foreign odds format to those of us outside of North America. And at first they appear a little confusing. But it is helpful to understand what these odds represent especially when listening to Americans speaking about gambling odds in sports broadcasts or podcasts. So, let’s see how we can convert Moneyline odds into their respective implied probabilities.

There are two instances of Moneyline odds: ‘minus’ moneylines and ‘plus’ moneylines.

The first are ‘minus’ moneylines. This is expressed as for example, -120. But what does this mean exactly? Well, let’s say bookmaker is offering odds of -120 for the Los Angeles Lakers to win a game. This is essentially saying that to win $100 you have to bet $120. In other words, if you place $120 on that outcome, you will receive a profit of $100.

The other instance are ‘plus’ moneylines. This is expressed as for example +180. In this case, let’s say bookmaker Deltin have offered odds of +180 for the New York Yankees to win a game. This simply means that if you bet $100, you will win $180.


So how do we convert the the ‘minus’ and the ‘plus’ moneyline odds into their implied probabilities? Let’s start out with the ‘minus’ moneyline conversion:

Converting ‘minus’ moneyline odds into implied probability formula:

Implied probability = ( – ( ‘minus’ moneyline odds ) ) / ( – ( ‘minus’ moneyline odds ) ) + 100

So let’s take an example, in which Deltin offers the following bet: San Diego Chargers to win against New England Patriots at odds -120.

Example: How to convert ‘minus’ moneyline odds to its implied probability

(- (-120) / ( (- (-120) ) + 100) = 120 / 220 = 0.545 = 54.5%

Multiplied then by 100, we get the implied probability percentage of 54.5%.

Converting a ‘plus’ moneyline is a bit different. Calculating the implied probabilities on these look like this:

Converting ‘plus’ moneyline odds into implied probability formula:

Implied probability = 100 / ( ‘plus’ moneyline odds + 100 )

So let’s take an example, in which deltin offers odds +180 for Los Angeles Lakers to beat Miami Heat.

Example: How to convert ‘plus’ moneyline odds to its implied probability

( 100 / 180 + 100 ) = 100 / 280 = 0.357 = 35.7%

Multiplied then by 100, we get the implied probability percentage of 35.7%.