Before we dive into odds conversion, let’s begin with a fundamental understanding of the different odds formats:

Decimal Odds

Decimal odds, also known as European odds, are expressed as a decimal number, typically greater than 1. For instance, if you have decimal odds of 2.00, you would double your stake if your bet is successful. The formula to calculate the probability from decimal odds is: Probability = 1 / Decimal Odds

For example, if the decimal odds for an event are 2.00, then a bet of $1 would win $2 if the event occurs because it is probability(2)/wager(1)

Fractional Odds

Fractional odds, commonly used in the UK, Fractional odds are expressed as a fraction, with the numerator representing the amount won and the denominator representing the amount staked. For example, if the fractional odds for an event are 3/1, then a bet of $1 would win $3 if the event occurs.

Moneyline Odds

Moneyline odds are the most common type of betting odds in the United States. They are expressed as a positive or negative number, with positive odds indicating the amount that would be won on a bet of $100 and negative odds indicating the amount that would need to be bet to win $100. For example, if the moneyline odds for an event are +150, then a bet of $100 would win $150 if the event occurs. If the moneyline odds for an event are -150, then a bet of $150 would need to be placed to win $100.

Example:

Let’s say that you are betting on a football game between the Lakers and the Miami Heat. The Lakers are the favorites, so their decimal odds are 1.50. The Heats are the underdogs, so their decimal odds are 2.50.

If you bet $100 on the Lakers, you would win $50 if they win the game. If you bet $100 on the Heat, you would win $150 if they win the game.

Now that we’ve explored the basics, let’s get into the nitty-gritty of odds conversion.

How to Convert Decimal Odds to Probability

Converting decimal odds to probability is straightforward. Simply use the formula mentioned earlier: Probability = 1 / Decimal Odds. Let’s illustrate this with an example:

Example: You have decimal odds of 2.50 for a football team winning. To find the probability of this outcome, use the formula:

Probability = 1 / 2.50 = 0.40 or 40%

So, there’s a 40% chance of the football team winning according to these odds.

How to Convert Fractional Odds to Probability

Converting fractional odds to probability involves a slightly more complex formula: Probability = Denominator / (Numerator + Denominator). Let’s look at an example:

Example: You encounter fractional odds of 3/2 for a tennis player winning. To find the probability, use the formula:

Probability = 2 / (3 + 2) = 2/5 = 0.4 or 40%

The probability of the tennis player winning is 40% based on these fractional odds.

How to Convert Moneyline Odds to Probability

Converting moneyline odds to probability depends on whether the odds are positive or negative. For positive moneyline odds, you can use the formula: Probability = 100 / (Moneyline Odds + 100). Here’s an example:

Example 1: You come across positive moneyline odds of +250 for a baseball team. To find the probability, apply the formula:

Probability = 100 / (250 + 100) = 100 / 350 = 2/7 ≈ 0.2857 or 28.57%

So, there’s a 28.57% probability of the baseball team winning with these odds.

For negative moneyline odds, the formula is: Probability = -Moneyline Odds / (-Moneyline Odds + 100). Here’s an example:

Example 2: You see negative moneyline odds of -150 for a basketball team. To calculate the probability, use the formula:

Probability = -(-150) / (-(-150) + 100) = 150 / (150 + 100) = 150 / 250 = 3/5 = 0.6 or 60%

The probability of the basketball team winning is 60% based on these odds.

Related: What Is Value Betting And How to Calculate It

How to Convert Probability to Decimal Odds

Converting probability to decimal odds is the reverse of the process we discussed earlier. You can use the formula: Decimal Odds = 1 / Probability. Let’s demonstrate this with an example:

Example: You believe there’s a 25% probability that a horse will win a race. To find the decimal odds, apply the formula:

Decimal Odds = 1 / 0.25 = 4.00

So, the decimal odds for the horse winning are 4.00.

How to Convert Fractional Odds to Probability

Converting fractional odds to probability involves a slightly more complex formula: Probability = Denominator / (Numerator + Denominator). Let’s look at an example:

Example: You encounter fractional odds of 3/2 for a tennis player winning. To find the probability, use the formula:

Probability = 2 / (3 + 2) = 2/5 = 0.4 or 40%

The probability of the tennis player winning is 40% based on these fractional odds.

How to Convert Moneyline Odds to Probability

Converting moneyline odds to probability depends on whether the odds are positive or negative. For positive moneyline odds, you can use the formula: Probability = 100 / (Moneyline Odds + 100). Here’s an example:

Example 1: You come across positive moneyline odds of +250 for a baseball team. To find the probability, apply the formula:

Probability = 100 / (250 + 100) = 100 / 350 = 2/7 ≈ 0.2857 or 28.57%

So, there’s a 28.57% probability of the baseball team winning with these odds.

For negative moneyline odds, the formula is: Probability = -Moneyline Odds / (-Moneyline Odds + 100). Here’s an example:

Example 2: You see negative moneyline odds of -150 for a basketball team. To calculate the probability, use the formula:

Probability = -(-150) / (-(-150) + 100) = 150 / (150 + 100) = 150 / 250 = 3/5 = 0.6 or 60%

The probability of the basketball team winning is 60% based on these odds.

How to Convert Probability to Decimal Odds

Converting probability to decimal odds is the reverse of the process we discussed earlier. You can use the formula: Decimal Odds = 1 / Probability. Let’s demonstrate this with an example:

Example: You believe there’s a 25% probability that a horse will win a race. To find the decimal odds, apply the formula:

Decimal Odds = 1 / 0.25 = 4.00

So, the decimal odds for the horse winning are 4.00.

How to Convert Probability to Fractional Odds

Converting probability to fractional odds requires some algebra. To convert a probability (P) to fractional odds, you can use the formula:

Fractional Odds = 1 / P – 1

Example: Suppose you believe a golfer has a 60% chance of winning a tournament. To convert this probability to fractional odds, use the formula:

Fractional Odds = 1 / 0.6 – 1 = 1.67 (rounded to the nearest hundredth)

This means the fractional odds are approximately 1.67/1.

How to Convert Probability to Moneyline Odds

Converting probability to moneyline odds is also dependent on the probability value. For probabilities greater than 50%, use the formula: Moneyline Odds = (Probability / (1 – Probability)) * 100. For probabilities less than 50%, use the formula: Moneyline Odds = ((1 – Probability) / Probability) * 100.

Example 1: You estimate that a soccer team has a 70% chance of winning. To convert this probability to moneyline odds, use the first formula:

Moneyline Odds = (0.7 / (1 – 0.7)) * 100 = 2.33 (rounded to the nearest hundredth)

So, the moneyline odds for the soccer team winning are approximately +233.

Example 2: You believe a horse has a 40% chance of winning a race. To convert this probability to moneyline odds, use the second formula:

Moneyline Odds = ((1 – 0.4) / 0.4) * 100 = 150

The moneyline odds for the horse winning are -150.

Related: How Much Should A Player Bet On A Game

How to Convert Decimal Odds to Fractional Odds

Converting decimal odds to fractional odds is a straightforward process. To convert decimal odds (D) to fractional odds, use the formula:

Fractional Odds = (D – 1)

Example: You have decimal odds of 3.50 for a tennis match. To convert these to fractional odds:

Fractional Odds = (3.50 – 1) = 2.50

The fractional odds for the tennis match are 2.50/1.

Odds Conversion Chart

The following table shows a conversion chart for the three most common types

Example:

Let’s say that you are betting on a basketball game between the Golden State Warriors and the Cleveland Cavaliers. The Warriors are the favorites, so their decimal odds are 1.50. The Cavaliers are the underdogs, so their decimal odds are 2.50.

If you bet $100 on the Warriors, you would win $50 if they win the game. If you bet $100 on the Cavaliers, you would win $150 if they win the game.

To convert the decimal odds to fractional odds, you would multiply the Warriors’ decimal odds of 1.50 by 1 and subtract 1 from the denominator. This gives you the fractional odds of 3/1.

To convert the decimal odds to moneyline odds, you would multiply the Warriors’ decimal odds of 1.50 by 100 and then subtract 100. This gives you the moneyline odds of +50.