Betting Odds Format: A Complete Guide

Understanding different odds formats is critical for making informed betting decisions.

Odds come in three main formats, with sportsbooks in the U.S. using mostly American odds that are defined with a plus (+) or minus (-) sign. Other formats include decimal odds (which are more prevalent in Europe) and fractional odds.

Odds are presented differently, but they mean the same thing when it comes down to wagering on a sporting event

What Are Betting Odds Formats?

In simple terms, betting odds are used to show the likelihood of an outcome for a specific event and to determine how much a bettor can win when placing a successful wager.

Knowing how to read and interpret different types of betting odds will help you place a smarter wager and potentially predict changes in a market.

It's easy for novice or beginner sports bettors to feel overwhelmed by the numbers involved, but these numbers are nothing to fear. Rather, embrace the odds for a more joyful experience and to maximize potential returns.

There are three main odds formats used around the world, with location and betting platforms determining which format is used.

Main Types of Odds Formats

Three main types of betting odds formats are used to present basically the same information with little to no difference to determine the implied probability of an outcome and the amount of a payout for a winning bet.

Each format, be it American odds, decimal odds, or fractional odds, has pros and cons, and since they are (for the most part) interchangeable, it’s a good idea to know a little about each format.

Betting odds are not just numbers, rather, they are determined using sophisticated algorithms to represent the probability of an outcome.

American Odds

American odds are the format of choice for sportsbooks in the States, so bettors in the U.S. are familiar with them.

Also referred to as moneyline odds, they are shown with a positive (+) or negative (-) sign in front of a number to represent the favorite and underdog in a specific event. It’s easy to calculate payments based on a $100 wager with plus odds showing the amount won on a $100 bet, and negative odds showing how much is needed to bet to win $100.

For example, if Team B wins at +150, a $100 bet wins $150. At -150, a bet of $150 is needed for a $100 profit.

Of course, any amount can be wagered.

Decimal Odds

Decimal odds are commonly used outside the U.S. Popular in Europe, Australia, and Canada, among other countries, decimal odds are easier to work with and understand.

The favorites and underdogs can be determined quickly by looking at the numbers.

The breakeven point is 2.00, with higher numbers giving more back on a win and lower numbers offering less of a potential return. The odds are the amount a bettor clears for every $1 wagered, including the original stake.

If the Jets are 2.50 and they win, a $10 bet has a total payout of $25. At 1.30 odds, the total payout would be $13 for a win of $3.

Fractional Odds

Native to a specific region, fractional odds are common in the U.K. and Ireland, giving them the term British odds.

They are presented as two numbers separated by a slash (10/1) or hyphen (10-1), and they represent the possible payout on a winning wager, not including the original amount bet. To win the number on the left of the slash, you would need to bet the number on the right.

For example, with odds of 10/1, a $1 wager earns a profit of $10. A $100 winning bet has a profit of $1,000 plus the original stake for a total payout of $1,100.

How to Convert Between Odds Formats

Although displayed in different formats, betting odds offer similar implied probabilities and payouts for the same event.

Odds do differ at various sportsbooks, but for the most part, they are almost the same.

If a bettor is more familiar with one format, he can use methods to translate from one format to another. You don’t have to be a mathematical genius, and a better understanding of odds aids the betting process.

Most reputable sportsbooks offer an odds calculator to assist in determining, but knowledge is a powerful weapon.

Decimal to Fractional

Understanding the basics is useful, especially if you don't have an odds calculator or conversion table to reference.

Going from decimal odds to fractional odds is easy; take the decimal and subtract 1. So, 5.00 – 1 = 4/1. It’s not always accurate, especially when the decimal isn’t a whole number, but it gets close.

Another example: 4.50 – 1 = 3.5/1, and for a whole fraction it’s 7/2.

Decimal to American

To convert decimal odds to American odds, you need two formulas, one for positive odds and one for negative odds.

For decimal odds larger than 2.00, take the number and subtract 1, then multiply that by 100. For instance: 2.50 – 1 = 1.5 x 100 for American odds of +150.

With decimal odds less than 2.00, the following formula is used: (-100) divided by decimal odds -1. With decimal odds of 1.50, we have -100 / 0.50 for American odds of -200.

Fractional to American

You’ve likely heard someone say they’ll give five-to-one odds on the outcome of a certain event. But what does that mean when translating to American odds?

It’s actually quite simple to convert fractional odds when there’s a positive fractional value. Divide the fraction, then multiply it by 100. In this case, 5/1 = 5 x 100 for American odds of +500.

There is a different format for a negative fractional value. Divide -100 by the fractional value of 1/2 for American odds format. Example: 1/2 = .5, then -100 / .5 gives the equivalent of -200 in American format.