Learning how to read Las Vegas odds is a prerequisite to success in sports betting. So, in this post, I’m going to explain Vegas odds as best I can.

In fact, once you understand Vegas lines, you can bet on sports online or offline just about anywhere.

## What Are Vegas Odds? (Meaning)

Las Vegas odds are the numbers that most (if not all) United States sportsbooks use to handle their betting. It’s a system that gives bettors the details about what they’re betting on. And it includes moneylines and point spread bets, among others.

This system has been in place since the 1930s when Nevada originally legalized sports betting. Oddsmakers from all over the country swarmed Las Vegas to get hold of the newly legal sports bettors.

They created secret handicapping systems that enabled them to offer bets with odds that favored their side of a wager often enough to generate a profit. These systems used many of the same stats used to create Vegas odds today, including:

- Historical performance
- Win/loss ratios
- Injuries

Today, the oddsmakers in Las Vegas are the masters of judging the relative odds of a bet winning or losing. In fact, most offshore gambling sites use the same odds that they’re using in Las Vegas.

## How to Read Las Vegas Odds

In Vegas, the sportsbook posts the odds on the big board. They update this digital ticker constantly in real time. When you see a line in the newspaper or on a website, you’re usually looking at something that was copied from a Vegas sportsbook’s board.

The board includes who the favorite is, who the dog is, and what the payout is for a winning bet. I saw an article on the web about this that said Vegas bettors read these boards hoping to win 60% to 70% of the time. That’s pie in the sky stuff. 60% is closer to the high end of the number of bets you can expect to win if you’re a great sports bettor.

### What Are Vegas Odds? They’re the Same Thing as American Odds

American odds all assume a betting unit of $100. If you’re betting more or less than that, you convert the odds based on the amount you bet.

The odds on the board in a Vegas sportsbook list the amount you can expect to win or lose with a bet on a favorite or an underdog.

If you’re betting on a favorite, the book lists – sign in front of them. That represents the size of the bet you’d need to place to win $100. For example, if a team is listed at -150, you must risk $150 to win $100.

The book lists an underdog’s odds a + sign in front of them, and this represents the amount you’ll win if you bet $100 and win. For example, if a team is listed as +150, winning your $100 bet results in winnings of $150.

No matter what kind of bet you place in Vegas, you’re betting on Vegas odds.

## Understanding Vegas Odds

Las Vegas odds (and American odds) represent an implied probability. The sportsbook pays an oddsmaker to estimate the likelihood of winning a bet. You can reverse-engineer the implied odds if you have a good understanding of Vegas odds.

In fact, if you’re serious about betting on sports, this skill is critical. Luckily, it’s also easy.

Most people are comfortable with thinking of probability in terms of percentages. Converting betting odds into a percentage is easier than you think, too.

Here’s the formula for when you’re betting on the underdog:

100 / (amount you’ll win + 100)

In the example from earlier, where a bet on the underdog pays out at $150, the formula looks like this: 100/ (150 + 100), or 100/250. Convert that fraction into a percentage, and you find out that the underdog’s implied probability of winning is 40%.

And here’s the formula for when you’re betting on the favorite:

amount you must risk / (amount you must risk + 100)

In the example I gave earlier, where you’re risking $150 to win $100, the formula looks like this: 150/(150 + 100), or 150/250. That converts to 60%.

## The Most Common Bets and How Vegas Odds Work with Each of Them

Of course, you have multiple bets to choose from. I’ve listed the most common of them here along with how to read each of them.

### Moneyline Bets and Vegas Odds

A moneyline bet is just a bet on which side is going to win a sporting contest. If you understood the last section, you know everything you need to about how the odds work.

The main thing to remember is that a bet on the favorite always pays out less than a bet on the underdog.

Here’s an example from a basketball bet.

-200

+150

The favorite is listed at -200, which means you must risk $200 to win $100.

The underdog is listed at +150, which means you will win $150 if you risk $100.

### Point Spread Bets and Vegas Odds

You’re probably wondering why I haven’t mentioned point spreads yet. Those are, after all, the most popular bets in Las Vegas.

And I haven’t mentioned them yet because you need to understand Vegas odds before thinking about point spreads.

A point spread is a handicap that oddsmakers use to make the odds of a team winning better, which drives more action.

In a point spread bet listing, the odds will look like this:

+4 (-105)

-4 (-115)

The first number is the amount that the team either adds or subtracts from their final score to determine the winning bet. The underdog is the team with the +, as they get to add the point spread to their score. The favorite must subtract the point spread for a bet to win.

Theoretically, this gives the teams each a 50% probability of winning. Or the book at least hopes that the point spread will drive an equal amount of action to either side of the contest.

In the example above, the amount in parenthesis is the amount you must risk to win $100. Notice that the numbers are slightly different. That difference is how the book makes its money — it’s called the vig, or vigorish. If the book gets equal action on each side of the contest, it still shows a profit.

### Determining the Winner

In case my explanation wasn’t clear enough, the underdog gets to add the point spread to the team’s score to determine whether they won. So, a team could actually lose a game but win a bet.

If the final score in the game was 20-17, and the underdog scored 17, you’d add 4 to their final score to determine the winner. Since 17 + 4 = 21, and since 21 is greater than 20, the bet on the underdog wins.

### Over/Under Bets and Vegas Odds

An over/under bet is the same thing as a totals bet. It’s a proposition bet on how high the total score for the game will be. You add both sides’ scores together to get the total and determine the winner.

You can bet that the total score will go over the book’s prediction, and you can also bet that the total score will go under the book’s prediction.

In a football game, for example, a total might be 39.5. If you bet on the over, you’ll win if the total score is 40 or higher. And, if you bet on the under, you’ll win if the total score is 39 or less.

Notice that the 0.5 makes a tie (or push) impossible with this bet.

## Conclusion – How to Read Las Vegas Odds

If I’ve done my job right, you now know how to read Las Vegas odds as well as anyone else.

In fact, if you can convert these odds into implied odds, you can start to get a feel for how good or bad a bet is.

If you think a team has a better chance of winning than 60%, and the implied odds are set at 60%, it makes sense to bet on that team.

Once you’ve placed a couple of bets, it will be even clearer. You can do that at any of the sportsbooks recommended on this site if you want to try it online.

Or you can go to Vegas and place bets at any of the sportsbooks there.