Odds Converter Tool and Helpful Charts

This handy tool instantly converts odds from one format to the next. It also calculates the implied probability of a set of odds. It’s super easy to use and it’s completely free.

Not sure what’s going on here? If you’re not familiar with sports betting odds and how they work, please take a look at our page that explains odds in sports betting flawlessly.

Alternatively, we’ve provided a quick overview of each of the different odds formats further down this page. We’ve explained implied probability too. Additionally, there’s an odds conversion chart for easy reference. And last but not least, there’s a list of calculations needed to convert the different formats, for anyone who’s interested in mathematics behind everything.

Implied probability is basically the conversion of odds into a percentage. That percentage then shows the likelihood of an outcome happening based on the size of the odds. High odds suggest a low probability of something happening, while low odds suggest a high probability of something happening.

For example, imagine a tennis player is +200 to win an upcoming match. This would be 3.00 in decimal odds, and 2/1 in fractional odds. The implied probability for these odds is 33.33%. In this example, the odds suggest that the player has a 33.33% chance of winning the match.

The following chart shows the different formats for various commonly used odds.

Since we’ve provided this tool, you don’t need to know the calculations required to convert odds from one format to another. In the interests of completeness, however, we’ve provided all of these calculations below. We’ve included examples too.

Although you don’t NEED to know these, it won’t do you any harm to learn them. After all, there may be times when you need to convert odds but don’t have access to our conversion tool.

There are two calculations for this. The first is used when converting positive moneyline odds. “y” is replaced by the relevant odds you want to convert.

Here’s an example, using +200 as the initial odds being converted.

The second calculation is used when converting negative moneyline odds. Again, “y” is replaced by the relevant odds you want to convert. Please note that for the purposes of this calculation, the negative sign in the odds is ignored.

Here’s an example, using -400 as the initial odds being converted.

The calculations for this conversion again depend on whether the moneyline odds are positive or negative. For positive moneyline odds, you create a fraction by placing the odds over 100. Then, if possible, you simplify the fraction. So, for +200, you’d create the fraction 200/100. This would be simplified to 2/1.

Negative moneylines work in the exact opposite way. So you create a fraction by placing 100 over the odds. The negative sign in the odds is ignored. So, for -400 you’d create the fraction 100/400. This would be simplified to 1/4.

There are two calculations for this conversion too. The first is for when the decimal odds are greater than 2.00.

You must add a positive sign to the result to get the correct moneyline odds. Here’s an example, using odds of 5.00.

Add the positive sign, and we get +400.

Here’s the calculation required when the decimal odds are 2.00 or less.

You must then add a negative size to get the correct moneyline odds. For this example, we’ll use odds of 1.50.

Remember we need to add a negative sign this time. So the converted odds are -200.

Converting decimal odds to fractional format is a three step process. First you use the following calculation.

Then you take the answer from that calculation and create a fraction by placing it over 100. In the third step, you simplify the fraction.

Let’s use 2.50 as an example. Here’s the first step.

The second step then gives 150/100. For the third step, you simplify the fraction. 150/100 simplifies to 3/2.

This is another conversion that requires two different calculations. The first is used when the odds are “odds against” (i.e. higher than evens).

A positive sign must then be added to get the correct moneyline odds. For the example here, we’ll use 3/1.

Now add the positive sign and you get +300.

The second calculation is used when the odds are “odds on” (i.e. lower than evens).

This time a negative sign must be added to get the correct moneyline odds. For this example, we’ll use 1/2.

Now add the positive sign and you get -400.

We’re almost done. This is the last of the calculations for odds conversion. You’ll be pleased to know it’s also very simple. Here it is.

For this example, let’s use 5/2.

That’s it! You now have all the tools you need to convert odds between any of the formats.