Whether you’re stepping foot inside a sportsbook for the first time or logging into a sports betting app, it’s normal to be confused or overwhelmed by all the numbers staring back at you. While these numbers may seem like a foreign language at first, have no fear because this article was written to help it all make sense.

Understanding sportsbook odds is an important part of betting because odds tell us exactly how much a wager will payout and give a general idea of how likely the bet is to win or lose. Keep in mind that odds are constantly fluctuating like the stock market based on news and other influences.

Understanding Different Types of Odds

There are three ways that odds are displayed: American odds, decimal odds, and fractional odds. American odds are usually the default odds displayed on North American sportsbook apps, but most sportsbooks give users the option to display them differently, so below is information about each style so readers can see which they prefer to work with.

American Odds Explained

If a sportsbook displays odds as a 3-digit (or sometimes more) whole number with a + or minus sign next to it, it’s using American odds. Examples include: -120, +260, -133, and +550. American odds immediately tell a bettor who the underdog is, who the favorite is, and how much money the bet will pay depending on the size of the wager. While American odds are the most common odds you’ll see in North American sportsbook apps or on your favorite sports betting podcast, they’re arguably the most confusing for a newcomer.

What Do the + and – Mean in Sports Betting?

In a standard sporting event with two teams (or individuals in a sport like tennis), there’s a favorite with a minus sign (-) next to its odds and an underdog with odds expressed with a plus sign (+). For the rare occasions when both teams are equally matched, it’s possible both sides have minus (-) odds or the odds are expressed as “EV” or “EVEN,” meaning “even money” (i.e. $100 wins $100). A wager with a plus sign (+) will always win more money than the original wager, while a bet with a minus sign (-) is always going to win less money than the original wager.

It’s easiest to understand American odds through the eyes of a $100 bettor. For instance, a winning $100 wager on a +240 underdog wins $240 and a +137 underdog winner uses a $100 wager to win $137. Of course, bettors are allowed to wager other dollar amounts as well and bet sizes scale easily. For example, a bettor wagering $1000 on that same +240 underdog would win $2,400 and someone who risked $15 wins $36.

A -140 favorite means $140 needs to be wagered in order to win $100 and a -320 favorite means $320 needs to be wagered to win $100. A $1000 wager at -320 odds pays $312.50 and a $25 wager at -320 pays $7.81. In person at a sportsbook, a bettor does this math before they walk up to the counter to place a bet, but the beauty of sportsbook apps is the payout is calculated instantly once the wager size is typed in. Our odds calculator is a useful tool at a sportsbook or for those seeking to better understand these odds.

Calculating Winnings with American Odds

When the odds are positive, the number after the plus sign tells the bettor how many dollars they'd win on a $100 wager. When the odds have a negative sign, the following number tells us how much we'd have to bet in order to win $100.

If a $100 bettor wins a +330 futures bet on the Houston Astros winning the American League West, they receive $330 in profit and also get back the original $100 wager for a total payout of $430. This can cause semantic confusion around the word “winnings”  because a bettor bragging, “I just won $430” could be corrected by someone reminding them, “You really only won $330” even though $430 was just deposited back into their account. Likewise, a $200 bettor who correctly predicted a -150 bet, would win $133.33 and also receive back the original $200 wager for a total payout of $333.33 ($113.33 of which is profit). See below for more information about the difference between winnings and a payout. 

Calculating Implied Probability with American Odds

You may recall from math class that probability refers to the likelihood of an event happening. Implied probability is expressed as a percentage and refers to the likelihood of a bet happening based on specific odds from a sportsbook. For instance, the implied probability of a -140 bet is 58.33% and the implied probability of a +360 bet is 21.74%.

For American odds with a plus (+) next to them, bettors determine the implied probability by dividing 100 by the odds plus 100. For instance, if the Tennessee Titans are +180 to win, then add 100 to the odds to get 280 and divide 100 by that 280 to get .3571 or 35.71%. For American odds with a minus (-) next to them, divide the odds by the odds minus 100. For instance, if the Chicago Bears are -218 favorites, subtract 100 from that to get -318. Then divide the original odds (-218) by that -318 number to get .6855 or 68.55% implied probability.

Decimal Odds Explained

Decimal odds, sometimes referred to as European odds, are less common in the United States, but a bit more straight forward. Decimals odds are displayed as a number with two additional numbers after a decimal point. For instance, a sportsbook might offer odds like these: 1.91, 1.50, and 3.40. Decimal odds are popular in several European countries as well as New Zealand and Australia.

If a bet wins more money than is being wagered, like in the case of an underdog, the first digit will always be “2” or higher, and if the bet returns less money than risked the first digit will be “1” or higher. Unlike American odds, there are no negative numbers with decimal odds and the lowest decimal odds will go is 1.00, which is equivalent to -99999 in American odds.

Calculating Winnings with Decimal Odds

To determine your profit on a bet with decimal odds, just multiply the wager amount by the odds and then subtract the original wager amount.

For example, a $100 winning bet on a team with 3.40 decimal odds (100 x 3.40 = 340 – 100 = 240) produces $240 in profit. Furthermore, a winning $200 wager on a team with 1.91 odds means $182 in profit based on this math: (200 x 1.91 = $382 – 200 = $182).

Calculating Implied Probability with Decimal Odds

Using decimal odds to calculate implied probability is a one-step process. Simply divide 1 by the decimal odds to receive the implied probability. For instance, with 3.50 decimal odds (1/3.50 = .2857 = 28.57% implied probability). Likewise, for 1.5 decimal odds, the math is: 1/1.5 = .6667 = 66.67% implied probability.

Fractional Odds Explained

Fractional odds are most commonly found in the United Kingdom, Ireland or horse racing events throughout the world. Fractional odds are sometimes referred to as “U.K. odds” or “British odds” and are usually expressed with a numerator and denominator separated by a slash, like this: 10/1, 9/2,  or 13/5. With this odds format, the denominator represents the wager and the numerator is the profit taken home if the bet is a winner. Note: Fractional odds are sometimes displayed with a hyphen (i.e. 10-1, 9-2, 13-5) instead of a slash.

Calculating Winnings with Fractional Odds

A $100 bettor would win $500 in profit on a bet with 5/1 odds and they’d win $1000 profit on a bet with 10/1 odds. At 13/5 odds, a winning $100 better would profit $260 and at 9/2 odds, a $100 bettor stands to win $450.

These outcomes above are a result of multiplying the wager by the fractional odds. For instance, 13/5 is 2.6, and 2.6 x 100 (wager) is $260, therefor a $100 wager at 13/5 odds produces a $260 profit.

Calculating Implied Probability with Fractional Odds

Imagine if the New England Patriots had 9/2 odds to beat the Cincinnati Bengals. These odds are essentially implying that if the Patriots played the Bengals 11 times (9+2 = 11), New England would win twice and lose nine times. Therefore if the Patriots would theoretically win 2 of 11 games, then the implied odds of Patriots winning are 18.18% because 2/11 is .1818. Here’s another example: Novak Djokovic is 2/5 to win a tennis match, so it’s implied that he’d win 5 times out of 7 matchups, and 5 divided by 7 is .71428, therefore the implied odds are 71.43%.

To calculate these implied odds above, we divided the implied number of wins (the denominator in the fractional odds) by the implied number of outcomes (numerator + denominator).

How Odds Correlate with Payouts

It’s important to keep in mind that “payouts” are different than profits/winnings, though people often mistakenly use these words interchangeably.

A payout is the total amount of money a sportsbook gives you after winning a bet (profit + original wager), whereas the profit doesn’t include the original bet amount. For instance, if a bettor risked $1000 on the Boston Red Sox at -140 odds, the bet would win $714.29 (profit), but the sportsbook would award the bettor with a payout of $1,714.29 ($714.29 profit + $1000 wager).

Many sportsbook tickets look like this:

Different sportsbooks might use different terminology, so in this case, the "Ticket Cost" is the wager, “To win” is the profit, and “To collect” is the payout.

Implied Probability

This article has demonstrated how to calculate implied probability (see above) whether a sportsbook is displaying American odds, decimal odds, or fractional odds. The concept of implied probability is an important one for bettors to be aware of as they shop for odds because at the end of the day the implied probability can help determine whether or not to make a bet.

The true probability of a coin landing on heads is 50%, but if a sportsbook offered -115 odds on a heads bet, that implied probability is 53.49%. In other words, the sportsbook is implying with their odds that heads will come up 53.49% of the time. Of course, we know the true probability is 50% so it’d be a good idea to stay away from that bet. However, the implied probability of +130 odds is 43.48%, so if a bettor was offered +130 odds on a coin coming up tails, that’d present good value because the odds are implying the event will happen 43.48% of the time and we know it’ll actually happen 50% of the time. Of course, sports betting is different from flipping a coin because we don’t know the true probability of a team winning or losing, so our true probabilities are subjective. Vigorish is the reason a sportsbook offers implied odds that are different than true odds.

What is the Vigorish?

Vigorish, AKA “Vig” or “juice” is essentially a fee or tax that’s cooked into betting odds by oddsmakers, and paid by players, to increase sportsbooks profit margins. For standard bets, the vigorish is usually around 10%, but sometimes the vigorish is 15% or more in certain situations like live betting. Vigorish is the reason that an event with true odds at 50% (a coin flip landing on heads for instance) will be offered at a -110 price. Without vigorish, a fair price would be +100, but instead bettors are offered -110 so if they win a $1000 bet at that price, the casino essentially pays them $909.09 and pockets the rest ($90.91).

How to Interpret Specific Betting Odds

The amount of information a bettor can glean from betting odds is immense. First, odds tell us how much vigorish is being charged by a sportsbook. For instance, look at the same game below at two different hypothetical sportsbooks and notice how Sportsbook A is charging less vig and is a better deal for the bettor (no matter which bet they make), while sportsbook B is charging more and is a better deal for the sportsbook.

Odds also tell us which team is theoretically more likely to win (the favorite) and which team is theoretically more likely to lose (the underdog). Instantly by looking at the tables above we can see that Kansas City is the favorite and Baltimore is the underdog because of the plus sign next to Baltimore's moneyline and the minus sign next to Kansas City's moneyline.

Furthermore, odds tell bettors how close a game is expected to be. For instance, the Chiefs – Ravens game above is expected to be closer than the Cardinals Bills game below and, even without the help of the point spread column, this if evident by the more extreme odds in the moneyline column.

What Does it Mean When Odds are Negative?

If a bettor sees negative odds, it means they’re dealing with American odds (see above) and they can expect that bet to win them less money than they risked on the bet. For instance, a bet with -145 odds means $145 will win $100 and a bet with -600 odds means $600 will win $100. Odds with a minus sign (-) are theoretically more likely to win than odds with a plus sign (+), but they’re also less lucrative.

What Does it Mean When Odds are Positive?

If a bettor sees odds with a plus sign (+) it means that a bet is going to return more money than wagered. Underdogs almost always have odds expressed with a plus sign. For instance, a wager with +155 odds means $100 wins $155 and a bet with +265 odds means $100 wins $265. A bet with a plus sign next to the odds means that bet will pay a lot better than a bet with a negative sign (-) but it’s also less likely to win.

Common Betting Terms Explained

Bettors regularly use terms that have completely different meanings outside of the betting world and that can cause confusion for new bettors. For instance, a bettor overheard saying, “I tried to bet the chalk, but I pushed,” would make perfect sense to another bettor, but might sound incoherent to someone who doesn’t gamble. Below are some common betting terms, and if they’re helpful, check out our sports betting glossary.

What is Chalk in Sports Betting?

Chalk refers to significant favorites. For instance, if a bettor never bets underdogs and only bets favorites who are widely expected to win, they might be called, “chalky.” If someone is “betting chalk” or “betting the chalk,” they’re wagering on the side of the team expected to win.

What is a Pick'em?

In a two-way contest where both teams are thought to have an equal chance of winning, oddsmakers may designate a game as a “pick ‘em” in place of a point spread. The term simply means the bettor is wagering on which team will win the game outright instead of wagering on the margin of victory.

What is a Push?

A push occurs when a bettor gets his/her money back after a bet doesn’t win or lose. For instance, if a bettor risks $200 betting on the San Francisco 49ers (-130) to beat the Dallas Cowboys and the game ends in a tie, then the bettor doesn’t win any money and collects their original $200 back. Another example of a push is if a bettor predicts the final score will be over 47 points and the game ends with a score of 24-23 (exactly 47 combined points). Note: Bets with totals or point spreads that aren’t a whole number (i.e. 13.5) can’t push.

What Are Vegas Odds?

“Vegas odds” is a bit of a misnomer because they’re also displayed by sportsbooks outside of Las Vegas and are not unique to Sin City. “Vegas odds” or “Las Vegas odds” are umbrella terms for the odds displayed at American sportsbooks. Vegas odds refer to the moneyline, point spread, and totals (over/unders) as well as the individual odds for each bet.