Decimal Odds Explained

American odds are the standard and most common option for US sports bettors, but other formats are more prevalent in other markets. Decimal odds, such as 2.0 and 1.91, are the primary option in most of Europe and other countries across the globe. In this quick guide, we’ll cover how to read them and the ins and outs of betting with decimal odds.

What are decimal odds?

Decimal odds appear as positive numbers with one or two decimal points. With decimal odds, the lower number indicates that a team is favored, while the higher number indicates the underdog.

How to read decimal odds

When you pull up a game listing at an online sportsbook, you’ll see the odds for the main bets first. For the NBA and other sports, that’s the moneyline, spread, and total odds. It’ll look something like this.

For moneyline odds, the lower of the two decimal values indicates the favorite, which in this case is the Milwaukee Bucks. Milwaukee is also a 3-point favorite on the spread in a game with a total line of 213 points.

Right next to the spread and total are the odds for those choices. The numbers tend to be in tight ranges here. For comparison, odds of 1.91 are the equivalent of -110 in American form.

What decimal odds tell you

At first glance, sportsbook lines help us figure out the favorites and underdog in a matchup, but there’s more to see. You can determine payouts and implied probability, as well as how sportsbooks see the game most likely playing out.

For example, the odds can be really close, such as 1.85 and 2.05 on the moneyline, which indicates a game that’s essentially a toss-up. The span could also be much larger — a potential mismatch of 1.50 and 3.50 — or in a medium range of 1.70 and 2.25, for example.

Reading the odds correctly is the first step, while understanding what they’re telling you gets you to the next level.

How to calculate payouts when betting with decimals

If you win your bet, your payout depends on the odds at the time you placed your bet. The total return will be your initial stake plus a profit for winning the wager. For decimal odds, you can easily estimate the return:

The potential return on decimal odds: stake * odds = payout

• Bet $100 at odds of 1.9
  • $100*1.9 = $190
  • The payout is your initial stake plus a $90 profit
• Bet $10 at odds of 2.25
  • $10*2.25 = $22.50
  • The payout is your initial stake plus a $12.50 profit

Online sportsbooks will display the potential return on the betting slip. However, it’s helpful to know how to calculate it quickly on your own, as it can help you gauge different wagers by simply looking at the odds.

Determining probability from decimal betting odds 

Sports betting odds quickly point us to the more likely outcome, but not all favorites and underdogs are the same. Enter the concept of implied probability. Essentially, we can take decimal betting odds and translate the numbers into the likelihood of either side winning in percentage form:

Implied probability from decimal odds: (1/odds)*100 = implied probability

• Example: Odds of 1.8 for the favorite and 2.05 for the underdog.
• Favorite: (1/1.8)*100 = 55.55%
• Underdog: (1/2.05)*100 = 48.78%

The implied probability can give you a better look at what the sportsbook views as the chances of either side winning. It can be a helpful tool when handicapping games.

Why do the odds move after the initial release?

Once the odds for a game become available, they won’t always stand still. Bettors can benefit when they get a more attractive number on the side that they want to wager on, but it can also go in the opposite direction. So what’s behind the movement in the odds? It’s typically one of two things:

• New information: Once the odds come out, a new factor could emerge, such as a major injury or a change in the weather forecast. Since this info wasn’t part of the initial calculation, the odds could move in response.  
• Betting action: Sportsbooks will respond to action from professional (“sharp”) bettors or groups of bettors. Often, this information will drive a book to adjust a number, which in turn leads to competing books adjusting theirs as well.

A move could be very slight, such as from 1.91 to 1.87, or it could be of a more dramatic variety, such as 2.0 to 2.3. For bettors, the answer is to do your best to track the moves until you’re ready to place your bets. Additionally, you can always shop around and compare the odds at multiple US sportsbooks before wagering.

Other types of odds

Where decimal odds are not the standard format, here are the other options:

• American odds: In the primary odds format in the US, the odds appear as three-digit numbers (sometimes more) such as -135 or +115. Negative numbers indicate favorites, and positive numbers indicate underdogs.
• Fractional odds: Fractional odds appear with a slash or hyphen, such as 9/2 or 4-1. As in horse racing, the lower the value, the bigger the favorite, while longer shots will have larger numbers.

How to convert decimal odds to another format

While some sportsbooks let you easily switch the odds display, others stick to the preferred method in their market. You can use an online calculator to figure the changes, but there are also formulas if you want to do it yourself:

Converting decimal odds to American odds

• Decimal of 2.0 or greater: (odds-1)*100 = American odds
  • Odds of 2.2
  • (2.2-1)*100 = +120
• Decimal between 1.01 and 1.99: -100/(odds-1) = American odds
  • Odds of 1.91
  • -100/(1.91-1) = -110

Converting decimal odds to fractional odds

• Decimal odds-1; convert result to fraction and reduce as necessary
• 1.8-1 = 0.8 = 8/10 = 4/5