Sports betting sites are designed to make money. Positive expected value, or +EV, betting accounts for this fact. Instead of gamblers following their guts and placing random wagers, +EV bets are wagers on lines that have higher odds of cashing than the odds implied by the price.
Does this sound confusing? It can be! In this +EV sports betting guide, we're going to break down the mystique and help explain what this is, how it works, and how you can start winning big with +EV wagering.
Expected value is, essentially, the difference between sports bettors’ expectations and a sportsbook’s. The first step to understand this is grasping that ever line suggests an implied probability. Each line suggests what the sportsbook has calculated that the probability of something happening or not happening would be.
Take, for example, a line of +120, which suggests an implied probability of 45.5%, or a line of -120, which suggests an implied probability of 54.5%. Or, to be most straightforward, a line of +100, which suggests an implied probability of 50%.
However, sportsbooks don’t typically make things that have a 50/50 chance of happening +100. Take a look at point spreads, for example, where the lines are always set to -110, with each side having an implied probability of 52.4%. Similarly, if you were to flip a coin and bet on it, sportsbooks would likely have odds of -110 for both heads and tails rather than just 50/50.
This margin between the actual odds of something occurring and the sportsbook’s odds is how betting sites win, and it is known as the vig. It is essentially a betting site’s take.
So, how does this relate to +EV? I’m getting there! What +EV betting does is factor in the implied probability and the vig to find value. Let’s consider an example.
If the Green Bay Packers are playing Houston Texans, and a sportsbook has odds of the Packers winning at -200 and the Texans at +175, the sportsbook has given the Lions odds of 66.7% to win, and the Texans an implied probability of 36.4%.
Even if a bettor thinks the Packers will win but believes the Texans have a greater than 36.4% chance of winning, the positive expected value would then be with the Texans.
Essentially, +EV bets find value by understanding how the odds work to exploit oversights by sportsbooks. It is betting according to value, not according to who a gambler believes will win.
If you want to find long-term gambling success, you are going to need to do more than trust your gut. Sportsbooks are profitable enterprises because they are reliant on gamblers betting according to what they want to happen, and making unwise decisions. Having an expected value betting system can help combat this.
Expected value sports betting can help mitigate the house edge. It is what can take a bettor from being a casual wagerer who is falling victim to sportsbook’s oddsmaking practices to a sharp, someone who is learning to exploit these practices.
Sportsbooks across the country have years of experience creating lines that yield long-term wins for the betting sites. There’s a reason they entice gamblers with sportsbook bonuses - most of the time, once you are signed up, they will profit off you.
+EV bets are a way to create a system that gives gamblers an edge. Instead of instinctual bets, relying on positive expected value gives bettors a reliable way of wagering that can yield longer-term profit.
Variance is a mathematical concept that is, essentially, the difference in results vs. expectations. Variance is higher when there are less results.
Consider if you flip a coin five times. Each time, there is a 50% probability of the coin landing on either side. The outcome can be less predictable, given that anything can happen in a smaller sample size. However, if you flipped a coin a thousand, the variance would likely be decreased because the sample size is much greater.
Variance lends itself to the concept of expected value betting. If you made five EV betting wagers grounded in math and reason, you might not be profitable just because of variance. But if this was your betting model, and you made a lot more wagers using this principle, the profits are likelier to line up with what is expected.
Understanding how to calculate positive expected value is a necessary step to cashing in. This is likely what most bettors will tend to struggle with the most. Below, we’ll give you a breakdown of how you can calculate EV.
The first step is finding the implied probability of something. The calculus is different for positive and negative lines. For a positive line, you do:
100 divided by the line + 100, or 100/(line+100). Let's say the odd is +150. You would do 100/(150+100), which would come out to 40%.
For a negative line, the formula is slightly different. The negative line calculation is:
The line divided by the line plus 100, or line/(line+100). For -150, this would look like -150/(-150+100), which comes out to 60%.
Once you understand the implied probability calculation, you can then do the final EV calculation. This is:
EV= (Probability of winning x winnings) - (Probability of losing x Stake).
Let's do a real-world example based on a line. The Buffalo Bills are +105 against the Chiefs, who are -125. Let’s say I elect to bet $10 on the bills. With this formula:
EV= (48.8x20.50) – (55.6x10), which would then be (1000.4)-(556)= 444.4.
The vigorish, or the vig, as we've mentioned, is the cut charged by sports bettors that are collected when bettors lose wagers. Also known as the juice, it is what ensures profitability for books.
Vigs differ according to each bookmaker, but lines tend to be set up to provide reliable profit for sportsbooks. Once you understand the implied probability of something, you can calculate the vig.
Consider the line for an Eagles vs. Commanders game. The Eagles have odds of -280, and the Commanders have odds of +230. To calculate the vig, you must add the implied probability on both sides together, so 73.7% + 30.3% (104). Subtract 100, and you'll find the vig, which here is 4%.
The vig reduces profitability for bettors by ensuring that the two lines will almost never equal 100%, reflecting the fact that there is always an imbalance in sportsbooks’ favour.
If you want to be a successful EV bettor, you are going to need to find a way to identify great EV betting options. This is something that takes time and skill, and most bettors aren’t likely going to be able to get it on their own instantly.
Below are some quick tips for identifying +EV betting options.
Not all sports betting sites are the same, and many target different audiences. There is a term online that you may have heard of, and that is “soft” and “sharp” bookmakers. These are two different things, and understanding the distinction can help with your betting.
Soft bookmakers are sportsbooks that are slightly slower to alter their odds according to changes around events, like injuries or weather updates. They are aimed at casual, less experienced bettors. Their odds are often less in keeping with the true probability of a match, making them perfect for +EV betting, if you can find the right line.
On the other hand is sharp bookmakers. These are more advanced sports betting sites geared to experienced bettors. They use advanced models and automation, and have odds that adjust rapidly and are more reflective to the “true” probability of an event.
Understanding whether bookmakers are soft or sharp is a crucial step for bettors looking to find value on online betting sites. The softer it is, the more chances there are to exploit lines in your favour.
One of the things that many sports bettors love about utilizing online betting sites is the bonus offers that many operators tend to have. Bonus offers come in many shapes and sizes, ranging from matched deposits to free bets. These offers can be great for +EV wagers.
Bonus bets provide users with money by matching users deposits or providing them with free bets. These can be great and helpful, however, it is worth noting that many sportsbooks place restrictions on these that make using them for value betting difficult.
For example, many sportsbooks will put wager restrictions on the bonus funds that dictate what odds you can bet on. For example, a wagering requirement could be no bets on odds of less than +100. This doesn’t eliminate positive expected value wagering, but it just restricts you and makes it harder to find value.
Many betting sites don’t attach these requirements. For example, a sportsbook might not have wagering requirements and give bettors a no-strings-attached $20 free bet. You can then use this as you please on a great positive value option!
The process of identifying and placing +EV bets can be very tricky, and bettors might need some time before they have mastered this difficult art form. Below, we'll walk you through a brief step-by-step guide to how you can start positive expected value betting with a real-world example to help clarify.
There are both benefits and challenges to +EV wagers. Let’s consider both the pros and cons of this way of betting.
There are certain common mistakes that seem to crop up often when bettors are +EV betting. To help you avoid these potential pitfalls, we’ve come up with a list of common mistakes. Below are some to be aware of.
One of the nice things about +EV wagering is that there are plenty of great resources available online for gamblers to use. While it may be complicated, these are tools designed to help out. If you are interested, we’ve come up with some resources that you should utilize on your +EV journey.
+EV betting is a data-driven way of betting that relies on implied probability to find value that exceeds what sportsbooks are suggesting. This is an advanced betting strategy with a lot of benefits for sports bettors. It helps reduce risk and come up with binding principles that can shape a long-term strategy. While things like variance and the inherent risk of sports betting are worth considering, it is still a great part of a bettor’s toolbox. With this guide in hand, we hope you are ready to begin your positive expected value betting journey.
Cameron is a 2020 graduate from the University of Southern California’s Journalism program. He is an avid sports fan and bettor, whose favourite teams include the Toronto Raptors, and the Chicago Bears. Cameron has been writing about and following sports since the age of 10, when he first fell in love with the NFL and NBA.
