Betting Odds Explained - The Complete Beginners' Guide

Are you looking to see how betting odds work on sportsbooks? Read our guide to understanding sports betting odds before you place your first wagers.

Do you have to be a math genius to understand sports betting odds? The answer is no. You don’t need to crunch numbers in a calculator or scrawl Einstein-style formulae across a giant whiteboard to get to the bottom of betting odds. They're easy to read when you know how they work, and our guide on betting odds explained is here to explain exactly that, so let's get started.

How do Betting Odds Work?

The short answer is betting lines tell you how much of your stake you'll win if you correctly predict the outcome of a sporting event. The odds are set by the sportsbook, based on how likely they think that outcome is.

On US sportsbooks, sports odds are generally stated as a number with a + or - symbol in front of them; on sportsbooks outside the US, you might see odds stated in fractions or decimals. We're going to stick with the first kind - moneyline odds, which shouldn’t be confused with moneyline bets as that is the market for backing a winner in a match.

It's worth noting that the odds don't tell you what you win in monetary terms as you'll also need to know the value of the bet. Does that mean that you need to work out some numbers after all?

No, the sportsbook does it all for you. When you pick a line on a sportsbook and enter your stake, the payout will be stated on the bet slip straight away, usually including the original stake.

How to Read Sports Odds: A Look at Moneyline Odds

US sportsbooks most commonly use moneyline odds (also known as American odds outside the US). These odds are shown with either a + or – sign before them. The number after a + sign tells you the amount you would win on a $100 bet. So, if you put $100 on at +100 you would get $100 in profit plus your $100 back, giving you a total return of $200.

When it comes to the negative odds, the number tells you how much you would need to wager to make $100. If the odds are -200, you’ll need to bet $200, which would give you back your $200 plus a $100 profit.

As an example, let's take a look at a moneyline bet, where you have to choose the winner out of two teams. Let's go for the New Orleans Saints vs New York Jets:

  • The Saints have odds of -230 to win. When I bet $10, my bet slip shows a return of $14.40.
  • The Jets have odds of +180 to win. My $10 stake would return $28 to me if they win.

As you can see, I get a much better return if I put my money on the Jets. Sorry Jets fans, but that’s because this particular sportsbook has determined that they're much less likely to win. The bigger a positive number in moneyline odds, the longer the odds and the less likely it is that the team will win (according to the sportsbook, anyway). On the other hand, the larger the negative number, the shorter the odds and the more likely they are to win.

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Points Spreads

Points spreads are the most popular type of bets in some sports, like basketball and football. In this case, you aren’t just saying that you think a certain team will win, you’re going a step further by predicting what the winning margin will be.

Odds on these bets are slightly harder to read because the + and - symbols are used to show the point spreads you're betting on, as well as the odds of the bet. Sportsbooks should display all this in a way that's easy to read, but make sure you take a good look so you know exactly what it is you're betting on.

We can see how it works by going back to the Saints vs Jets game for some more numbers.

  • The New Orleans Saints at -5.5 have odds of -115. The first number is the points spread that I'm betting on, and the second number is the odds for that bet. That means a $10 bet gives me a total return of $18.70 if the Saints win by a margin of 6 or more.
  • The New York Jets at +1.5 have odds of +163. Betting $10 and getting it right here gives me back $26.30 if the Jets lose by 1 or they win.

In this example, the points spread bet can give me back more or less than the moneyline, depending upon the exact bet I place. The stronger the favorite, the bigger the odds will generally be on a small margin, while a game that is evenly matched will have more attractive odds on bigger winning margins.

In the case of the Saints, I got longer odds on the points spread than on the moneyline. That makes sense, because it's more likely that they will win by any margin - in other words, 1 point or more - than they will by 6 points or more, and that's reflected in the odds.

What About Parlays?

A parlay bet is where you link together several bets on the same bet slip, and you need each and every one of them to win. If this happy event occurs, you’ll collect a bigger win than you would have done by betting individually on each outcome, because the odds are much longer that every one of them will come in. This can be done on the same game too. 

Example:

  • NY Knicks at +148 on a money line bet vs the Indiana Pacers. A $10 bet gives me a possible return of $24.80.
  • The Washington Wizards at -240 on a moneyline bet vs the Detroit Pistons. With a $10 wager, I would get $14.20 back.
  • So, in total, I've bet $20 and won $39, including my stake.

If I were to place both of those bets as a $20 parlay, the odds would be +252, and if both parts of the bet win, the payout would be $70.40. I'd be paid out nearly twice as much as if I placed individual bets, and that's because the odds of both results being correct are much longer due to the parlay being less likely to win compared to single events as a result of the smaller probability.

The more bets you add to a parlay, the longer the odds get, even if you're picking heavy favorites. You'll usually find that the sportsbook has a limit on the number of bets you can parlay, too. 

Other Types of Bets

The other kinds of sports bet you find all work in the same way. You can bet on things like Patrick Mahomes to score the most TDs, Mike Trout to hit the first home run in a game, or Russell Westbrook to get the most rebounds. This adds some extra spice to the game, but you can use the same betting odds principles I’ve looked at here.

Just choose the bet you like the look of and add in your staked amount to see how much you could win. Before long, you’ll see that it becomes second nature to work out the return based on the odds, even before it appears on the screen.

The Juice and How It Affects the Odds

All sportsbooks build their odds with a degree of profit in mind. This is known as the 'juice' or 'vigorish' (see our guide for definitions), and it means that the odds aren’t quite as good as they could be if the betting company decided to be generous and not make any money from their customers.

So how does this work? Well, the sportsbook calculates the odds on each event so that regardless of the outcome, they make a profit. Let's take an example - an over/under bet on the game between the Pittsburgh Steelers and the Minnesota Vikings. We're betting on whether both teams will combine to score over or under 43.5 points - and remember, there are only two possible outcomes.

  • The odds on the over are -105, meaning a $100 bet would win you $195.23 if it came in.
  • The odds on the under are -115, which would result in a payout of $186.95 on a $100 bet.

In our example, the sportsbook has taken bets totaling $200, but the most it will have to pay out is $195.23, leaving the remaining $4.77 as their cut. If the under comes in, the sportsbook's cut would be even more: $13.05. That's the juice, and you'll find that it's included in the odds on all sportsbooks in the US. It usually works out at between 4% and 5% of the bet, but it can be much higher or lower, depending on the sportsbook and the market you're betting on, so shop around.

Betting Odds Explained: Fractional & Decimal

Outside of the US, you'll find that sportsbooks show odds stated in fractions or with decimals.

If we look at fractional odds first, we can quickly identify good value at a glance. Events backed as favorites by sportsbooks will have a denominator (bottom number) larger than the numerator (top number). For example, the Celtics are favorites to win their next match with odds of 1/2. 

Understanding what kind of return this will produce is done simply by multiplying your wager by the odds, with the addition of your initial wager returned as well. We like the betting odds provided for the Celtics game, if we backed them with a $5 wager and they'd won, we'd expect a profit of $2.50, and our $5 returned as well, giving us a total of $7.50. 

Decimal odds are a little less common and get used when we begin to deal with much larger numbers as they can be much easier to read than traditional fractions. A good rule of thumb is that the favorites will be given odds between 1 and 2. If the betting line is given at 2, then you'll receive the same amount as your initial wager.  

Betting Odds Explained

American Odds

Fractional Odds

Decimal Odds

Probability

-10000

1/100

1.01

99.01%

-500

1/5

1.2

83.33%

-200

1/2

1.5

66.67%

+/-100

1/1

2

50%

+150

3/2

2.5

40%

+250

5/2

3.5

28.57%

Conclusion

You'll hopefully take away some important lessons when looking to understand sports betting odds. A comprehensive understanding can help you identify the best value provided by sportsbooks, now head over to our odds comparison tool for the best NFL odds and much more. 

FAQ

How do Betting Odds Work? 

Odds will indicate the probability for a certain event to happen. Using the odds, you'll be able to work out how much money you stand to win if your bet lands. 

How to Understand Betting Odds? 

Odds are shown with either a + or a - in front. With a + in front, the figure that follows is the amount you stand to win if you bet $100. If there is a - ahead, this is the amount you'd need to bet to win $100. 

How to Read Sports Betting Odds?

Odds with a - ahead of them have a greater probability. The larger the negative number, the shorter the odds and the more likely they are to win. However, this will be reflected in your winnings.