What is EV?

For more information about how to use the plugin and the features it includes, check out our Arbitrage Scanner.

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What Is Sports Betting Expected Value?

Most sports bettors have heard about expected value, but few are familiar with its true meaning. Even fewer apply the concept to their bets. Here’s everything you need to know about expected value and why it’s arguably the most important factor for your sports betting ROI.

What Is Sports Betting Expected Value?

At its simplest, expected value in sports betting is a way to measure the probability gap between a bettor’s expectations — and the sportsbook’s.

Oddsmakers assign their probability through betting lines, which bettors see assigned to all moneylines, point spreads, and totals and any other bet type. Almost all legal U.S. sportsbooks use American odds, with positive figures (such as +100, +222, etc.) assigned to the underdog and negative figures (-120, -155, etc.) given to the favorite.

In this system, the line number increases as the likelihood of winning decreases, and the line number decreases as the likelihood of winning increases.

This means a +100 underdog is more likely to win than a +240 underdog (according to the book). Conversely, a -190 favorite is more likely to win than a -120 favorite.

Bettors can convert these line numbers into an implied probability using tools like our Betting Odds Calculator.

For example, if a book assigns a team — let’s say the Seahawks against the Patriots — a +100 line, that translates to a 50% winning probability, or a coin flip.

If a bettor believes that in this game the Seahawks actually have a greater than 50% chance to win, they would assign a positive expected value (+EV). If that bettor believes the team has a less than 50% chance to win, they would assign a negative expected value (-EV).

Why is Expected Value Important for Sports Bettors?

Weighing bets by expected value gives sharp bettors a fundamental advantage over most other bettors and one of the few edges they can take against a sportsbook.

One common beginner sports bettor mistake is scrambling through the board last minute, hoping to pick the day’s winners. Those looking for expected value, or +EV, consider the lines (and, by extension, probability) oddsmakers give to every game, often as early as possible, and try to figure if a bet is overvalued or undervalued.

The best NFL bettors make a habit of finding value early in the week. By Thursday, oddsmakers have adjusted their lines, and in an efficient market, value bets are only available for a short time before the market catches up.

Positive expected value betting is a foundational method to sports betting, one that casual bettors, often referred to as “the public,” don’t use enough.

A casual bettor is more like a roulette player hoping their color is called. A +EV bettor is a stockbroker looking to sell high and buy low.

As much as most sports bettors overestimate their betting acumen, it is all but impossible to win long-term by merely hoping to find winners. Sportsbooks have spent decades evaluating hundreds of thousands of sporting events. They employ the best oddsmakers, programs, and algorithms to find the most efficient lines. Even the most profitable bettors win “only” around 55%-56% of bets.

Cost of the Vig

Virtually every retail and online sportsbook charges at least a 5 percent fee (4.54% to be exact) on the betting line, also known as the vigorish or “vig.” For example, if a sportsbook assigns both teams a 50% chance to win, both teams’ lines are -110 (52.38% implied probability) instead of +100. This means bettors are paying what is essentially an extra 5% levy on every bet, win or lose. A bettor needs to win 52.38% of their bets just to break even.

To identify bets that have value despite the vig, you can use our Value Bets Scanner.

All that being said, sportsbooks historically hold between 5% and 8% profit on total money wagered. Smart bets can, at the very least, keep bettors afloat to play recreationally.

What it Looks Like to Place a Bet With Positive Expected Value

To use another analogy, a +EV bettor is like a shrewd supermarket shopper. The intelligent shopper notices when an item’s prices are higher than they were on a previous visit and finds a substitute accordingly. Similarly, +EV bettors shop across the online sports betting industry to find the biggest discrepancies between what they think will happen and what the book, through its betting lines, implies will happen.

For more tips on finding arbitrage opportunities, check out our Arbitrage Scanner, which helps locate discrepancies between bookmakers.

How do I Calculate Odds to Find +EV?

It may seem that taking probability from a betting line is a complicated formula, but it’s actually the simplest component of EV betting.

To quickly convert betting odds into probability, use our Betting Odds Calculator. It simplifies the calculation and helps you identify potential +EV bets more efficiently.

From there, a bettor can make a +EV bet by not simply predicting if a team will win, lose, or cover, but by weighing the likelihood such an occurrence happens against the probability given by the book.

The Price of the Vig: A Classic Example

Bettors may notice the probabilities in the above example don’t add up to 100%. This is due to the vig, which is applied to virtually every wager.

Since sports betting inherently includes this cost, finding opportunities where expected value exceeds the vig is key to long-term success. To identify these opportunities, use our Value Bets Scanner for bets that offer potential profit despite the vig.

How do I Calculate my Expected Value?

If all bettors only bet on +EV bets, sportsbooks would go out of business. Unfortunately, bettors have no sure-fire way of knowing precisely which bets have positive expected value. However, our Arbitrage Scanner can help identify potential mismatches in odds across different bookmakers.

More Tips for Positive Expected Value Sports Betting

If a bettor wants to be financially solvent long-term, they should make dissecting expected value a part of their process. Here are a few more tips that will help you do just that:

Don’t Bet on Your Favorite Team.

Many bettors enjoy the extra thrill of money riding on their favorite team’s competitions. Not +EV bettors. If you’re betting with your heart, you aren’t taking into consideration expected value. When placing a wager, it’s time to take off your jersey; your favorite team should be the one that gives the best value that day.

Don’t Bet on Everyone’s Favorite Team.

Just as a bettor shouldn’t consider their emotional attachment when considering a bet, they shouldn’t buy into the general public’s favorite teams, either. Popular teams often have inflated odds, creating a potential +EV opportunity to fade high-profile teams.

Don’t Bet on Everyone’s Favorite League.

This contrarianism extends to not just teams but sports and leagues themselves. Smaller leagues or niche sports, like those identified using our Arbitrage Scanner, often provide greater value as sportsbooks may not pay as close attention to these markets.

Watch Out for Home Favorites.

In some markets, sportsbooks see lopsided action on hometown teams. Value bettors should consider their local sportsbooks' home teams when considering a bet, especially if they see value on their opponents.

Be Wary of Heavy Favorites.

Bettors tend to love betting on the best teams, inflating the favorite’s price and reducing its value. Use our Value Bets Scanner to spot when underdogs have better value.

The Best Bet is Usually No Bet.

Sometimes, neither the favorite nor the underdog is worth a bet. On an NFL Sunday, many bettors will try their luck at every game of the day. A +EV bettor only bets on those which they think there is value. Use our chatbot for real-time assistance on betting strategies and identifying valuable betting opportunities.

Shop Around.

Sharp bettors shop around for the best lines. A line of +155 against +150 may not seem like much to a novice, but for a +EV bettor, every additional implied percentage point goes a long way toward long-term success. Use our Arbitrage Scanner to compare odds across multiple sportsbooks.

Look Early, Look Often.

True sharps pounce at lines when they’re at their most vulnerable, usually right after they’re released. To identify value before the market adjusts, explore options using our Value Bets Scanner to catch opportunities early.

Should I Consider EV for my Sports Bets?

Only if you want a chance to break even long-term. The sportsbook has every conceivable advantage, which is compounded further by the vig. The best (and, for all intents and purposes, only) way to counter is to try to find value bets. You and your bank account will be much better off doing so.

Learn More

For more detailed guidance, try our chatbot for real-time assistance on betting strategies and expected value calculations.