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How Sports Betting Odds Work

by August 7, 2018

For many of you, this article is going to provide information you already know. For those just getting into sports betting or considering it in light of the Supreme Court finally opening the doors to legalization, before you start placing bets “on the reg,” it is important to understand what you’re looking at.


Let’s start with the most basic of basics: what is a vig? If you’re looking at a particular betting option and you see +100 or Even Money, that’s pretty easy to understand: you will win the same amount as your bet. The lines are all based off of a presumed bet of $100. So at +100 or Even Money, if you bet $100, you win $100.

If you see a line that has a “-“ in front of it, that number is what you would have to risk to win $100. If you see a line that has a “+” in front of it, that number is what you would win if you risked $100. This is known as the “vig” or “juice.” It is the advantage the book inherently gives itself for booking your bet. For example, if you placed a bet on a -150 favorite, you would have to risk $150 to win $100. If you placed a bet on a +150 underdog, you would win $150 if you risked $100. When entering a wager, a sportsbook will always presume that you are entering what you want to win when betting a favorite and what you want to risk when betting an underdog. So if you submit a bet of $50 on a -200 favorite, the book will assume you want to risk $100 to win $50. Conversely, if you submit a bet of $50 on a +200 underdog, the book will assume you want to risk $50 to win $100.

In football, most lines will be -110 on each side if you are betting against the spread. Money lines are different. A money line is when the side you pick simply has to win. Point spreads required a favorite to win by more than a certain amount or an underdog to lose by less than a certain amount. If the Patriots are 7 point favorites over the Dolphins, that line will likely be -110 for both Patriots -7 and Dolphins +7. However, if you bet the money line, you will likely see something like Patriots -400 and Dolphins +275.

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Profit Margin

So you may be thinking, if the point spread is there to equalize the two sides, why isn’t it even money? Great question. Have you ever been to a casino? Surely you have. Think about a roulette wheel. You can bet black or red and double your money if you win. But your odds of winning aren’t 50%. There are two green slots on the roulette wheel where both black and red bettors lose. The house always has a slight edge. As I mentioned a bit before, in sports betting, it is no different. -110 essentially means the two sides are equal in terms of your chances of winning, but the house does not care who actually wins – its goal is to secure about the same amount of money wagered on each side of a game so that, regardless of the outcome, the house makes money. When you’re betting at -110, the house has +110. If $100,000 is bet on the Patriots -7 in the example above and $100,000 is bet on the Dolphins at +7, the house automatically makes $10,000. If you win 50% of your bets, you will lose money. In order to break even or make a small profit, you have to win about 52.5% of your bets. That number can fluctuate based upon the vig. If you are betting heavier favorites, your win percentage will have to be higher. If you are betting more underdogs, then your win percentage will have to be lower. It is important to understand that the terms “favorite” and “underdog” in this context refer to the vig, or, in other words, the actual betting odds, not the point spread.

Coming Soon

There are numerous ways to analyze betting odds, lines, trends, and other information to try and gain an advantage so you can eclipse the winning percentage necessary to profit. Be on the lookout for future articles covering the various intricacies of sports betting and the things to look for when deciding whether to place a particular bet.

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Jason Katz is a featured writer at BettingPros. For more from Jason, check out his archive.

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