Sports Betting Odds Guide: American, Decimal, and Fractional Explained

Entering the world of sports betting can be overwhelming, but understanding sports betting odds is a huge help. Put simply, knowing how odds work is essential to determining payouts and identifying favorites and underdogs.

There are three types of odds: American, decimal, and fractional.

Understanding American Odds

One of the most popular forms of sports betting odds in the United States is American odds, which are also known as moneyline odds. American odds are the standard at most US sportsbooks.

In the simplest terms, if it's a ‘-‘ in front of the odds, you must bet that much to win $100. If it's a ‘+' in front, you must bet $100 to win that much. The ‘-‘ denotes a favorite, while the ‘+' denotes an underdog.

Caesars odds accurate at time of posting (Aug 19,2025)

American Odds: Moneyline Example

Let’s look at an example of how American odds work using a theoretical NFL moneyline wager (a bet on who will win the game). The line for the game will look like this:

As we mentioned, the ‘-‘ in front of the number shows the favorite in the game (Commanders), and the ‘+' in front shows the underdog (Cowboys). Let's look at a couple of examples to paint a clearer picture (using the odds above):

• If you successfully bet $130 on the Commanders (the favorite) at -130 odds, you would win $100 in profit, for a total payout of $230 (your original stake plus your winnings).
• If you successfully bet $100 on the Cowboys (the underdog), you would win $150 in profit if they win, for a total payout of $250 (your original stake plus your winnings).

American Odds: Spreads & Over/Unders

One of the more unique aspects of American betting lines is that spread bets and totals can be incorporated. In these bets, oddsmakers handicap the wager so that the implied probability is 50-50.

Here's an example of a spread using American odds:

Both teams often have odds of -110 for spread betting, though this can vary slightly. In this example, betting $110 on either team would return $100 in profit if your team covers the spread.

⚠️ Note: For spread bets, a “push” (tie) occurs when the margin of victory equals the spread. To avoid this, sportsbooks often add 0.5 to the spread.

Explaining Decimal Odds

Decimal odds are more common outside the US, especially in Europe. Here's an example of how a decimal odds bet for an NFL game would look:

The team with lower decimal odds is the favorite, while a higher number indicates the underdog.

In this example:

• If you successfully bet $1 on the Seahawks (1.50), you would receive $1.50 total ($1 stake + $0.50 profit).
• If you successfully bet $1 on the Saints (2.50), you would receive $2.50 total ($1 stake + $1.50 profit).

Fractional Odds, Explained

Fractional odds are popular in the UK and frequently used for futures betting, such as predicting championship winners. Here's an example of a fractional odds bet for the Kansas City Chiefs to win the 2026 Super Bowl:

In this case, if you bet $10 on the Chiefs at 7.5/1, you would win $75 in profit (7.5 × $10) plus your original stake, for a total payout of $85. 

Simplifying fractional odds:

• The first number represents your potential profit for each unit wagered.
• The second number represents the unit.

For example, 11/5 means you would win $11 for every $5 wagered, 5/2 is $5 for every $2 wagered, and 8/3 is $8 for every $3 wagered.

Sports Betting Odds Comparison

In Europe, odds are shown as fractions like 3/1, which means for every $1 you bet, you’d win $3 in profit. When converted to American odds, 3/1 equals +300. Both formats reflect the same implied probability (25%).

The image below shows an example of a -110 American odds converted to fractional and decimal odds, as well as the potential payout and implied probability:

Most sportsbooks allow you to toggle between odds formats. Understanding each format helps you find the best odds across platforms.

Which Sportsbook Has the Best Odds?

Odds vary between sportsbooks, so it’s always smart to shop around. Lines can shift based on betting activity. For instance, if most bettors take the under on a total bet (known as a public betting trend), the sportsbook might adjust the odds to balance the action.

Below is an in-depth look at the odds quality at every major US sportsbook:

What is the Spread?

You often hear the term “cover the spread“ regarding sports betting odds. The spread is commonly used in football and basketball betting. It's the expected number of points a team will win or lose by, set by oddsmakers.

In this example:

• A bet on the Patriots (-5) requires them to win by at least six points to cover the spread.
• A bet on the Dolphins (+5) wins if they win outright or lose by four points or fewer.

If the Patriots win by exactly five points (e.g., 27-22), it’s a push, and you get your stake back. However, if the spread were -5.5, there would be no possibility of a push.

FanDuel odds accurate at time of posting (Aug 19,2025)

Other Popular Bet Types

The smartest way to bet on sports is to hunt for the best odds. If you can find a value bet in any way, shape, or form, you should consider using it to grow your bankroll. That’s why it’s important to consider a wide range of bet types, such as:

• ✅ Totals (Over/Under): Betting on whether the total points scored in a game exceed or fall short of a set number (e.g., Over 45 points in Giants vs. Eagles).
• 🎯 Prop bets: Betting on specific player or team outcomes (e.g., Russell Wilson passing yards, first touchdown scorer).
• 📈 Futures: Long-term bets on events like championship winners (e.g., Super Bowl champion).
• 🔀 Parlays: Multiple bets combined (all must win, typically three or more legs).
• 🔥 Live Betting: Betting on an event as it happens, with constantly changing odds.

Sports Betting Odds Calculator

A betting odds calculator is a valuable tool for bettors, helping to:

• ✅ Input betting odds (American, decimal, fractional)
• ✅ Calculate potential payouts
• ✅ Especially useful for parlay bets

⚠️ Final Tip:  Use a betting calculator for complex bets like parlays or when comparing odds formats to ensure accurate potential payouts.

How to Get the Best Odds

Understanding sports betting odds—whether American, decimal, or fractional—gives you an edge when evaluating bets. These formats are simply different ways of expressing the same probability, so choose the one you prefer.

By comparing odds across sportsbooks and exploring different bet types, you can increase your chances of finding value bets and growing your bankroll.