You should already know that the Eagles are the favorite to win and that you should expect less than even money on a correct pick here. You should also know that the Falcons are the favorite, and you should expect better than even money on a correct pick here. Having this in mind every time before you start your calculations will protect you from making a mistake and calculating the completely wrong direction.
Oddsmakers want you to gamble on underdogs as well as favorites. They set points spreads that encourage balanced betting. They analyze the strengths and weaknesses of each team, factoring in won-loss record, strength of schedule, results against common foes, key injuries, recent performance and previous games between the teams. They also rate the value of home field advantage and consider the game day weather forecast where relevant. If they see heavy wagering on the favorite, they will increase the point spread during the week to spur more betting on the underdog. If more money is going on the underdog, the spread will decrease as game time nears.
Let’s say that the Mavericks and the Magic are playing in an upcoming game, and both teams are equal counterparts. Let’s say that the odds for that game are as follows. You will never see these odds, though, because in this example, the sportsbook is not set to make any money if they achieve their goal of getting money on both sides of the bet. But we need to look at it for you to better understand things.
Is there value there? Yes. Are you going to make money off that bet? Well, it depends. If you’re only able to make a bet like this once, then you’re most likely going to lose. In order to realize that value, you’ll need to be in a lot of similar opportunities. If you have a very long-term betting strategy, then you can probably get away with making this bet. But if you’re looking for some more regular profit, you might want to steer clear of this. The odds say that the team is only going to win the game a little under 3 times for every 100 times they play. There is value there, but it depends on your betting strategy if you want to make that bet.
In this example the Jets are listed as four-point favorites (-4) over the Bills and the 49ers are three-point underdogs (+3) against the Seahawks. So, if you bet $110 on the favored Jets, they must defeat the Bills by more than four points in order to win $100. If you bet $110 on the underdog 49ers you will win $100 if they win outright or lose by less than the three-point spread. If the final score happens to end up exactly on the number it's a tie, or 'push,' and you get your money back.
This is called line shopping and is an integral part of sports betting, especially with moneyline bets. Most good sports bettors will have accounts on lots of different sportsbooks so they can check the lines on every bet they are making. Whichever book has the best lines for them is where they’re going to place their bet. To be honest, with how easy it is to shop lines online, the only reason you wouldn’t is if you were too lazy and didn’t care enough about your bottom line.
What does this mean for how you win a point spread bet? Glad you asked. To win a point spread bet, you pick the team that you think is going to "win" after the point spread differences are calculated in. Let's look at an example that will make this clearer. In the above chart, we see that you can bet the San Diego Chargers at -3. This means, as we already stated, that the sportsbook thinks the Chargers are the favorites and that they are going to win by three points. Here are three potential scores of the game:
That was all before Charles McNeil, a math teacher from Chicago, invented the concept of the point spread. An avid gambler, McNeil created what he called “wholesaling odds” and started his own bookmaking operation in the 1940s. He started out offering this new style of betting on football, but his business model grew to include basketball.  McNeil changed the way sports betting was done, and his legacy lives on today in what we now call the point spread.