How To Read Sports Betting Odds

U.S. online and retail sportsbooks provide American odds. However, you might find the occasional fractional or decimal display, so it’s important to know the differences.

• American odds: Displayed as a “+” or “-” followed by a number (-110, +560, etc.)
• Fractional odds: Displayed as a fraction (7/1, 9/2, 10/15). To turn those fractional odds into American odds, just do the division. Let’s take 9/2: 9 divided by 2 is 4.5, which is the same as +450.
• Decimal odds: Displayed as 1.2, 8.0, etc.

They all tell you how much you’ll win if a bet is successful.

American odds include either a “+” or “-” symbol that precedes the numeric odds for both sides of a bet.

Example:

American odds usually indicate a clear favorite (side that’s expected to win) and clear underdog (side that’s expected to lose). Any team with a “-” in front of its odds is the favorite, while the “+” denotes the underdog.

It helps to understand American odds by using hypothetical $100 bets, which we’ll do using the above Arizona Diamondbacks-San Francisco Giants example.

A $100 wager on Arizona would pay out $188 in profit, plus the return of your original $100 bet ($288 total). We know this because, as the underdog (team expected to lose), the Diamondbacks have the higher potential payout.

An easy way to remember: The number attached to the “+” symbol reflects how much you would win for every $100 wagered. So a $100 bet would win $188, a $200 bet would win $376 ($188 * 2), a $300 bet would win $564 ($188 * 3), and so on.

The Giants’ side of the equation is slightly trickier. With San Francisco as the betting favorite—which we know because of the “-” symbol—bettors would have to wager $225 for a profit of $100 (plus the return of your original $225).

In simple terms:

• Odds with a “-” indicate what you’d need to bet to profit $100.
• Odds with a “+” indicate how much you’d profit with a $100 bet.

What if My Standard Bet Isn’t $100?

While an example of a $100 bet is helpful for learning how American odds work, we don’t recommend it in practice unless you can afford it. In fact, you’re encouraged to establish betting units that fit your budget. The good news is the process scales with your wager.

So let’s say your standard betting unit is $25, and you want to bet the Diamondbacks at those +188 odds. To calculate your potential winnings, just multiply your wager ($25) by 188, then divide by 100. To make it even simpler, just multiply your wager by 1.88.

Either way, the answer is $47. Add that profit to your initial $25 stake, and your total payout is $72.

How much do you need to risk if you want to win $25 betting on the Giants at -225 odds? Convert the odds to a decimal (so -225 becomes 2.25) and multiply that figure by the amount you want to win. So: 2.25 * 25 = 56.25.

Thus, a $56.25 wager on the Giants has a potential profit of $25. If the Giants win the game, you will collect a total of $81.25 ($56.25 original bet + $25 in winnings).

Implied Probability

Implied probability is a more advanced metric. It’s helpful to understand if you’re looking for a chance at long-term profit. If you prefer to keep things casual, you don’t need to concern yourself with implied probability—but it doesn’t hurt to understand how it works.

So let’s once again use the Diamondbacks-Giants example to walk through how to determine implied probability.

Before we jump to the math, it’s important to know that the implied probability calculation differs for favorites and underdogs. Let’s start with the formula for underdogs (plus odds):

100 / (Odds + 100) = implied probability

Using the Diamondbacks for our example, the equation is: 100 / (188 + 100). That yields an answer of 34.72. In other words, Arizona has a 34.72% chance to win this game (based on its +188 odds).

Now, let’s figure out the implied probability for the other side of the bet (Giants -225). The formula for favorites (negative odds):

Odds / (Odds + 100) * 100 = implied probability

Plugging in the Giants’ -225 odds, the equation looks like this:

225 / (225 + 100) * 100 becomes 225 / 325 * 100

225 / 325 = 0.6923. Multiply that number by 100 and you get 69.23.

So, the implied probability of San Francisco winning is 69.23%.

Now, let’s use these two implied probability numbers to figure out the house edge. First, add the two percentages:

34.72 + 69.23 = 103.95.

After subtracting 100 from that total, you get the house edge: 3.95%.

As a bettor, you want the number representing the house edge to be as low as possible.

Fractional odds are most common at British and Irish sportsbooks, as well as in horse racing. While this format doesn’t appear at U.S. sportsbooks, it can be helpful to understand if you want to calculate implied probability (or if you simply prefer how fractional odds look over American odds).

The main symbol associated with fractional odds is precisely what you imagine: the same forward slash “/” that’s used to denote fractions.

Calculating Winnings

Fractional odds make calculating your potential winnings simple. We’ll look at the calculations using odds from an Oakland A’s-Texas Rangers game.

Odds of 7/5 mean you’ll win $7 for every $5 you wager on the A’s. Conversely, the Rangers’ odds of 5/8 mean you need to wager $8 to win $5 on Texas.

Another way to look at it:

If the first number is larger than the second, you’re betting on the underdog for a higher potential payout.

If the first number is smaller than the second, you’re betting on the favorite, which will pay out less because the favorite has a higher likelihood of winning.

The easiest way to calculate your possible winnings when using fractional odds is to assume you’re betting the amount that appears at the bottom (or right) of the fraction to win the number at the top (or left).

Saying it out loud can help. With 7/5 odds, it’s “I can win $7 for every $5 I bet.” So, a $20 bet could win you $28 (total payout of $48). With 5/8 odds, it’s, “I can win $5 for every $8 I bet.” So, a $24 bet would pay $15 (total payout of $39).

Implied Probability for Fractional Odds

Calculating implied probability using fractional odds is much easier than with American odds:

Bottom number / (Bottom number + Top number) x 100 = implied probability.

So, here’s the equation for the Oakland A’s at 7/5 odds:

5 / (5 + 7) x 100 = 41.67%

Using the same calculation, you’ll see the implied probability for the Rangers (5/8 odds) is 61.54%.

You might find these in the wild from time to time, especially in Europe, but the format is rarely used in the U.S. Still, a core understanding of decimal odds is important should the format ever come up on your sports betting journey.

Calculating Winnings

Let’s use another baseball example to illustrate how decimal odds work.

Decimal odds are refreshing in their simplicity: Multiply your wager by the amount displayed, and you’ve got your total payout (initial wager and profit).

In this scenario, a $10 bet on the Brewers would pay out $23 (net profit of $13). The same $10 bet on the Twins would pay $16.60 (net profit of $6.60).

Understanding decimal odds is that easy.

Implied Probability for Decimal Odds

Also easy to understand: how to determine implied probability using decimal odds.

Here’s the calculation:

(1 / Odds) x 100 = implied probability

So for a bet on Milwaukee, the equation is (1 / 2.3) * 100. That’s an implied probability of 43.48%.

For the Twins, it’s (1 / 1.66) * 100, which is an implied probability of 60.24%.

Clearly, in a three-way battle between American odds, fractional odds and decimal odds, the latter is the hands-down winner when it comes to calculating both potential winnings and implied probability.

Now that you have a basic understanding of the three most common odds formats, all that’s left to do to become an expert is practice. After a while, you’ll be able to glance at the odds and immediately know how much you’d win with bets of many sizes.

On the hunt for a sportsbook that lets you choose between the three formats?

Major U.S. sportsbooks typically display American odds by defeault, but some have the option to view odds in alternate formats if desired.

North America bettors should brush up on the pluses and minuses because that’s the format you’re most likely to see, unless you plan on moving overseas.