How Do Betting Odds and Lines Work?

If you’re just getting started with sports betting, you may not know that not all sportsbooks post the same odds for a particular game. Odds will generally be close between all of the different sportsbooks, but they can differ for a few reasons.

Below we’ll walk you through the basics of sports betting odds, including how books set them and where you can take advantage as a bettor.

Who sets official sports betting odds?

Many sportsbooks set their own odds. The books have their own mathematical models that will produce numbers that make sense, and oddsmakers can adjust from there based on a variety of factors that the computers may not have accounted for.

They have it down to a science, and with some bets, the sportsbook odds are almost completely analytics-based.

For live betting, bettors can place money on the action as the game is going on. Obviously, sportsbooks cannot have a person dedicated to changing the numbers around every second, so they have algorithms that do the heavy lifting.

What do you mean by “odds” and “lines”?

A betting “line” is a margin set by sportsbooks to establish a parameter for betting on either the favorite or underdog. Betting lines refer to a point spread or the total number of points scored in a particular game.

When a sportsbook releases its lines, each line will show the odds that come with betting on a certain outcome.

Odds show how much of a chance oddsmakers believe a certain outcome will occur, and that is reflected in how much money bettors will receive with a winning bet.

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What kind of odds can I find at sportsbooks?

If you plan to bet on team sports — particularly football betting and basketball betting — there are three main types of wagers you are likely to come across:

  • Moneyline: This is the easiest of the main bets to understand. With the moneyline, you are simply betting on which team will win the game. Odds will reflect the perceived talent level of the competing teams, so you would receive a larger payout by successfully betting on the underdog to win than you would if you correctly bet on the favorite.
  • Point spread: The point spread, meanwhile, is oddsmakers’ way of evening the playing field. Instead of simply winning the game, the favorite has to beat the underdog by a certain number of points, which the book sets for each game.
  • Over/under: With this bet — which sportsbooks may also call the total — it doesn’t matter which team wins. All that matters is the total combined score in the game. After doing their calculations, the oddsmakers set a number, and bettors may wager on whether the total number of points will finish higher or lower than that figure.

Learn more about the differences in betting the moneyline vs. the spread.

Other popular betting options include futures, where you can bet on something months in advance like which team will win the Super Bowl, and prop bets, like how many passing yards a particular quarterback will have in a game.

If you are unfamiliar with how to read odds, it is fairly easy to understand. All the pluses and minuses in sports betting can be a bit overwhelming at first, but it’s easiest to understand them by using $100 as the benchmark.

  • With an odds number like -110, that means a bet of $110 would win $100 in profit if successful.
  • If the odds were -350, it would take a winning bet of $350 for a profit of $100, and so on.

If there is a plus sign, meanwhile, the calculations are a bit different.  For example:

  • If the odds show something like +140, that means a $100 wager would result in a $140 profit on a winning bet.

Online & local odds vs. Vegas odds

For a long time, Las Vegas was one of the only places fans could legally bet on sports in the US. That started to flip in 2018 when the US Supreme Court overturned the Professional and Amateur Sports Protection Act.

This ruling left it up to individual states to legalize sports betting within their borders. A growing number have done so. So, Vegas odds are not all that important anymore because not all of the odds come out of Las Vegas anymore.

With big-name legal sportsbooks operating outside of Nevada, they can set odds without relying on Vegas to be the go-to option. At this point, there is very little difference between online and local odds vs. Vegas odds.

Are odds the same in all sports?

No. Based on the difference in the way scoring works across the various sports, odds won’t be the same across all sports. Sports like football and basketball feature a lot of points, so there will be big differences in the point spreads, for example.

However, for a sport like baseball that features less scoring, it uses what sportsbooks call a run line instead of a point spread. Instead of the spread varying as in football and basketball, the run line in baseball is a standard 1.5, and the odds reflect how likely each team is to cover that.

When & why do odds change?

Even with all the research that goes into setting an original odds line, odds can change drastically from when they come out to when the game they apply to begins. The main reason for the odds to change is that sportsbooks react to what bettors do.

If sportsbooks release odds for a certain outcome and 90% of bettors pick one side, oddsmakers adjust the numbers to entice other bettors to wager on the side getting just 10% of bets.

With a significant percentage of the money to one side, that increases the potential liability for the sportsbook if the high percentage side wins. Sportsbooks don’t want that. Sportsbooks want the action to be even on both sides, because the risk is minimal, which is what they are looking for.

Other reasons for the odds to change might include injury news, roster movement, weather concerns, etc.

How does an odds algorithm work?

Sportsbooks have tons of data to use. They take that data and try to set the perfect number based on their mathematical formulas.

Sportsbooks have their own algorithms for spitting out numbers, and while they will generally be the same or similar, some books are more aggressive in trusting the numbers instead of adjusting based on the rest of the market.

Odds algorithms can factor in any number of variables, and they will update as new data comes in. Sportsbooks can find the areas where they are most successful against the bettors and keep that strategy going. And if there is an area where the book is getting exposed, it will work quickly to rectify the issue.

What are the “best” odds?

The best odds are the odds that give you the highest possible payout. This is where line shopping comes into play.

While the numbers will usually always be fairly close, there can be discrepancies. By checking multiple online sportsbooks, you can guarantee yourself the highest possible return on a winning bet.

If you find a bet you love, check every sportsbook you have an account for and place your wager at the sportsbook with the best odds. This may seem like a small thing, but it will pay off in the long run.

How do I know odds are fair?

Sportsbook betting odds can be subjective, but to start with, you want to use a legal Texas sportsbook. For a long time, those who were not in Vegas bet on sports through illicit local bookies or offshore sportsbook accounts.

Now that the industry is being regulated in many states, there are consequences if a regulated sportsbook isn’t acting fairly. Previously with bookies or offshore sportsbooks, they could simply decide not to pay you, and you would have few legal options.

Fairness in betting odds is ultimately up to you. If you take a look at a bet, but you do not like the odds, do not bet on it and consider placing your action elsewhere.

What does it mean when one sportsbook has outlying odds?

On rare occasions, one sportsbook could be offering completely different odds compared to the rest of the market, and there could be a few reasons for this. One of them might be that the book knows something that the others do not. Another potential reason might be if a successful regular bettor at that particular book put in a huge bet on one outcome, and the sportsbook is being aggressive in getting bettors to take the other side.

In general, the odds will tend to be close among the various operations, but if there is one different from the rest and offering better odds on what you are leaning toward, that is where you might be able to take advantage.

How do you calculate your own sports odds?

The best of the best in sports betting do their own handicapping. They build their own models and systems to try to gain an edge over the sportsbooks. If you want to do this, you’ll need to be more advanced in the numbers you use than a regular sports fan.

For example, if you want to bet on college football, do not use yards per game as one of your key stats to look at. Offenses can be extremely different in terms of the number of plays they run, so a better stat would be yards per play.

If you stop thinking like a sports fan and start thinking like a sports bettor, you will have a better shot at success.