Fraction Odds to Decimal, American, Probability (Converter)

There are three common ways how bookmakers state betting odds: Decimal Odds, Fraction Odds, and American Odds.

We all are used to a different type of odds interpretation, so sometimes we need to convert one type of odds to the other (for example fraction odds to decimal) in order to understand odds in a way we are most used to. 

So, at Fantasy Football Reports, we prepared a useful betting odds converter for you. It can help you during your decision-making process in Fantasy Football or in your betting strategies. 

You can use our fraction odds converter right away, but if would like to know more about these types of odds and how they are calculated, keep reading. 

Let’s explain them all.

1. Fraction Odds Explained

Fraction Odds are typical for the UK and Ireland, and are often referred to as traditional odds. They are written with a slash “/”, and for example, the odds 3/1 reads “three-to-one”.

They represent the potential profit you can make relative to your stake. For instance, if you come across odds of 5/1, it means for every unit you stake, you stand to win five times that amount. So, a £10 bet at 5/1 would yield a profit of £50, making your total return £60 (including your initial stake).

2. Decimal Odds

Decimal odds, often used in mainland Europe, Australia, and Canada, represent the total amount you’ll get back for every unit staked – this includes your original stake. For example, odds of 6.00 mean that for every £1 you bet, you’ll receive £6 in return (your £1 stake plus £5 profit). The conversion from fractional to decimal is straightforward: simply divide the numerator by the denominator and add 1. Using our previous example, 5/1 as a decimal would be 6.00.

3. American (Moneyline) Odds

These odds are popular in the United States and come in two varieties: positive and negative. Positive figures, like +500, indicate how much profit you’d make on a $100 bet. In this case, a successful $100 bet would yield $500 profit. Negative figures, like -150, show how much you need to stake to make $100. So, you’d need to bet $150 to make a $100 profit.

3. Implied Probability

Every set of odds, regardless of format, implies a certain probability of an outcome occurring. This is crucial for bettors who want to find value in their bets. The implied probability is the reverse of odds; it tells you how often the bookmakers expect an outcome to happen.

Implied probability from fracional odds:

For fractional odds, the formula to calculate implied probability is:

Implied Probability=(Denominator)/(Denominator+Numerator)

For example, with odds of 5/1, the implied probability is 1/(5+1) = 1/6 = 16.67%. This means the event is expected to happen approximately 16.67% of the time.

Calculating Implied Probability from Decimal Odds:

To determine the implied probability from decimal odds, you’ll use the formula:

Implied Probability = 1 / Decimal Odds

For instance, if you have decimal odds of 3.00, the implied probability would be: Implied Probability = 1/3.00 = 0.3333

Calculating Implied Probability from American Odds:

The calculation for implied probability from American odds varies based on whether the odds are positive or negative:

For Positive American Odds (e.g., +200):

The formula is:

Implied Probability = 100/(American Odds+100)

For example, with American odds of +200: Implied Probability= 100/(200+100)=100/300=0.3333

This translates to a 33.33% chance of the event occurring.

For Negative American Odds (e.g., -150):

The formula is:

Implied Probability = American Odds/(American Odds-100)

Using American odds of -150 as an example:

Implied Probability = (−150)/(-150-100)=150/250=0.6

This means there’s a 60% chance of the event occurring, according to the odds.

4. Conversion Guide

Converting between odds formats can seem daunting, but with a few simple formulas, it becomes straightforward:

How to Convert Odds From Fractional to Decimal?

Divide the numerator by the denominator and add 1.

Decimal Odds=(Numerator)/(Denominator) + 1

For example, if you have fraction odds 5/3, you can convert them to decimal this way: Decimal Odds = 5/3 + 1 = 2.67

How to Convert Odds From Decimal to Fractional?

Subtract 1 from the decimal odds to get the numerator and use 1 as the denominator. Simplify if necessary.

For example, let’s decimal odds to be 3.5. Fraction Odds = (3.5 – 1)/1 = 2.5/1 = 5/2 

How to Convert Odds From Fractional to American?

If the fraction is greater than 1 (e.g., 5/1), multiply the numerator by 100 for the positive moneyline odds. If the fraction is less than 1 (e.g., 1/5), divide -100 by the fraction to get the negative moneyline odds.

For example, for Fraction odds 5/2, the American odds are (5*100)/2 = 500/2 = 250

For Fraction odds 2/5, the American odds are (-100/1)/(2/5) = -250

How to Convert Odds From American to Fractional?

For positive moneyline odds, divide by 100. For negative moneyline odds, divide 100 by the absolute value of the odds.

For American Odds 350, the fraction odds are 350/100 = 3.5/1 = 7/2

Remember, while these conversions help in understanding odds across formats, the implied probability remains consistent across all.

How to Convert Odds From Decimal to American?

For Decimal Odds Greater Than 2.00:

  • Subtract 1 from the decimal odds.
  • Multiply the result by 100.

American Odds = (Decimal Odds – 1) * 100

If you have decimal odds of 2.50, the conversion to American odds would be: American Odds = (2.501) x 100 = 1.50 x 100 = +150

For Decimal Odds Less Than 2.00:

  • Subtract the decimal odds from 2.
  • Divide -100 by the result.

American Odds =100 / (2 – Decimal Odds)

If you have decimal odds of 1.80, the conversion to American odds would be: American Odds =100 / (21.80) = –100 / 0.20 = –500

How to Convert Odds From American to Decimal?

For Positive American Odds (e.g., +200):

  • Divide the American odds by 100.
  • Add 1 to the result.

Decimal Odds = (American Odds / 100) + 1

If you have American odds of +150, the conversion to decimal odds would be: Decimal Odds = (150 / 100) + 1 = 1.50 + 1 = 2.50

For Negative American Odds (e.g., -150):

  • Divide 100 by the absolute value of the American odds.
  • Add 1 to the result.

Decimal Odds = (100 / Absolute Value of American Odds) + 1

If you have American odds of -500, the conversion to decimal odds would be: Decimal Odds = (100 / 500) + 1 = 0.20 + 1 = 1.20

Common conversions

Decimal Fraction American Implied Probability (%)
Matej Šuľan

Fantasy Football enthusiast with two top 1k finishes in FPL. Best FPL overall rank: 119th in 2019/20 season. Five top 500 finishes in UCL Fantasy, best overall rank: 23rd in 2018/19 season. Founder of Fantasy Football Reports.