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.

ODDS CONVERTER
American Odds:
Decimal Odds:
Fractional Odds:
Implied Probability:

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.

About Moneyline Odds

  • Also known as American odds.
  • Used primarily in the United States.
  • Can be positive or negative.
  • When positive, the number shows how much you could win from a $100 stake.
  • When negative, the number shows how much must be staked to win $100.
$10Stake
Odds of
+100
$20Potential Return

($10 win + $10 initial stake)

$10Stake
Odds of
+150
$25Potential Return

($15 win + $10 initial stake)

$10Stake
Odds of
-200
$15Potential Return

($5 win + $10 initial stake)

About Decimal Odds

  • Also known as European odds.
  • Used primarily in Europe, but increasingly popular worldwide.
  • Are always a number greater than 1.00.
  • The number shows the multiple of your stake returned, including your initial stake.
$10Stake
Odds of
2.00
$20Potential Return

($10 win + $10 initial stake)

$10Stake
Odds of
5.00
$50Potential Return

($40 win + $10 initial stake)

$10Stake
Odds of
1.50
$15Potential Return

($5 win + $10 initial stake)

About Fractional Odds

  • Also known as British odds or traditional odds.
  • Used primarily in the United Kingdom, but their use is declining.
  • The first number in the fraction shows you how much you can win per amount in the second number staked.
$10Stake
Odds of
2/1
$30Potential Return

($20 win + $10 initial stake)

$10Stake
Odds of
5/2
$35Potential Return

($25 win + $10 initial stake)

$10Stake
Odds of
1/2
$15Potential Return

($5 win + $10 initial stake)

What is Implied Probability?

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.

This doesn’t mean that this is the player’s EXACT chance of winning the game.

In sports, the probability of something happening is usually subjective. There are several factors to take into account and there’s always a chance of the unexpected. No one can state definitively the exact probability of a player or team winning a game they’re taking part in. There’s an element of personal opinion involved.

Calculating the implied probability is useful though. It helps us decide whether or not we think a bet offers any positive value. We should always look for positive value when betting, and it exists when our estimated probability of an outcome happening is greater than the implied probability that the odds on that outcome suggest.

Confused? Don’t worry! It’s not as complicated as it may seem. To make this easier to understand, let’s continue with the example of the tennis player at +200 to win his match. As we’ve said, the implied probability here is 33.33%. So if we think that the player has a GREATER than 33.33% of winning, then it makes perfect sense to bet on him. If we think his chances are less than 33.33%, it’s wise not to bet on him.

If you’d like a more complete explanation on this subject, there’s an article in our sports betting guide that explains value and implied probability in further detail.

Odds Conversion Chart

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

Moneyline Decimal Fractional
-500 1.20 1/5
-400 1.25 1/4
-250 1.40 2/5
-200 1.50 1/2
-150 1.66 4/6
-125 1.80 4/5
-110 1.91 10/11
Moneyline Decimal Fractional
+100 2.00 1/1 or Evens
+110 2.10 11/10
+125 2.25 5/4
+150 2.50 6/4
+200 3.00 2/1
+250 3.50 5/2
+350 4.50 7/2

Odds Conversion Calculations

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.

Moneyline format to decimal

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.

(y + 100) / 100

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

(200 + 100) / 100 = 3

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.

(y + 100) / y

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

(400 + 100) / 400 = 1.25

Moneyline format to fractional

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.

Decimal format to moneyline

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

(y – 1) x 100

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

(5 – 1) x 100 = 400

Add the positive sign, and we get +400.

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

100 / (y – 1)

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

100 / (1.50 – 1) = 200

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

Decimal format to fractional

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

(y – 1) x 100

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.

(2.50 – 1) x 100 = 150

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

Fractional format to moneyline

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

(y) x 100

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

(3 / 1) x 100 = 300

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).

100 / (y)

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

100 / (1 / 4) = 400

Now add the positive sign and you get -400.

Fractional format to decimal

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.

(y) + 1

For this example, let’s use 5/2.

(5 / 2) + 1 = 3.50

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