Positive Expected Value Explained: How to Find +EV Edges in Sports Betting

Learn what positive expected value (+EV) means and how to identify profitable +EV bets. Discover bet sizing strategies, understand why EV is theoretical, and learn why line shopping is critical for long-term success.

The term "positive expected value," often shortened to "+EV," is fundamental to profitable sports betting. If you're serious about long-term success, understanding +EV is essential.

This guide explains what positive expected value means, how to identify +EV opportunities, and the strategies you need to maximize your edge over time.

What is Positive Expected Value

For a bet to have positive expected value, the probability of winning must be higher than what the odds imply. If your estimated win probability exceeds the break-even point, you have a +EV bet.

Conversely, if your win probability is lower than the break-even point, it's a negative EV (-EV) bet that loses money over time.

Example: You want to bet on a team as 3.5-point home underdogs. The sportsbook offers -110 on both sides, meaning they're holding approximately 2.4% of wagers.

For the underdog bet to be +EV, you need it to win more than 52.4% of the time (the break-even point). If you believe the team will cover more than 52.4% of the time, the bet has positive expected value.

This is the foundation of smart, profitable sports betting. You don't need to predict outcomes perfectly—you just need to find mispriced lines where your edge exceeds the bookmaker's margin.

How to Identify +EV Bets

Identifying +EV bets requires estimating the probability that a wager will win. There are two main approaches:

Projections-Based Modeling

This method calculates probability based on on-field data, player stats, team performance, and other measurable factors. You might be familiar with this approach from win probability estimates or fantasy projections.

Projections-based models analyze historical data to predict future outcomes. They consider factors like offensive and defensive ratings, player efficiency, weather conditions, and matchup history.

Market-Based Modeling

Market-based models assume that some odds—and the bets placed on them—are sharper than others. Instead of calculating probability from on-field data, you compare prices across different bookmakers.

Sharp bookmakers (those with high limits and sophisticated pricing) tend to have more accurate odds than soft bookmakers (public-facing books with higher margins).

When a sharp book lists a bet at -150 but a soft book offers +150 on the same outcome, there's likely value on the soft book's line. The sharp book's price reflects more accurate probability, making the soft book's odds potentially profitable.

However, understanding which books are sharper and knowing when your edge overcomes each book's hold can be difficult. This is where automated tools help.

FairOdds Terminal automatically compares odds across 200+ bookmakers, identifying +EV opportunities by comparing sharp book prices to soft book prices. The platform calculates expected value, recommends bet sizes using fractional Kelly Criterion, and helps you focus on finding market inefficiencies rather than predicting game outcomes.

Expected Value is Theoretical

It's crucial to understand that expected value in sports betting is always theoretical. Unlike card games with fixed probabilities, sports outcomes are uncertain and driven by assumptions.

The concept of EV originated in formal statistics and investing, then moved to card games like poker. In poker, you can calculate precise probabilities because a deck has exactly 52 cards with set possibilities. Sports don't have these fixed parameters.

In sports betting, we estimate probabilities using models that compare possible outcomes to average results. We can run scenarios and regressions, but these are always assumptions based on incomplete information.

Before a game is played, we can only input assumptions about teams, players, and conditions. Reality happens when the game is played, bringing all the uncertainties that humans introduce—uncertainties that don't exist in card games.

This means you'll never know exactly what your win probability is for any given bet. Your best approach is to have a theoretical +EV based on sound analysis.

This theoretical nature has important implications for bet sizing and volume. Both depend on how confident you are in your perceived edge.

Bet Sizing Strategies

Since EV is theoretical, controlling bet sizing helps manage uncertainty. There are two main approaches:

Uniform Bet Sizing

Uniform bet sizing means betting the same amount on every wager. This approach is straightforward and prevents over-betting your bankroll when your theoretical win probability is lower than expected.

However, uniform sizing has drawbacks:

• You miss opportunities to maximize growth on large +EV situations
• You can't capitalize when you spot bets with huge expected ROI
• You might under-bet when your edge is smaller than you thought

If you notice a bet with a massive expected ROI, you might want to bet more—even if that ROI is only theoretical.

Kelly Criterion Betting

The Kelly Criterion is a mathematical formula that adjusts bet size based on your edge and bankroll. It helps maximize long-term growth while minimizing risk of ruin.

Kelly betting allows you to:

• Bet more on larger edges
• Bet less on smaller edges
• Protect your bankroll from over-exposure

Many bettors use fractional Kelly (betting a fraction of the full Kelly amount) to reduce variance. This is especially important when confidence in your edge is lower or when you're betting into small theoretical edges.

Important considerations:

• Small edges increase variance: A 10% edge comes through 10x more often than a 1% edge. Not all value is created equal.
• Volume matters: Small edges require significant betting volume to show consistent profits.
• Risk tolerance: Even if Kelly suggests a large bet, consider your personal risk tolerance and the robustness of your projections.
• Life EV: Making huge bets can hurt your "life EV" if they put you at financial risk. Stay within your comfort zone.

Proper bankroll management is essential regardless of which sizing approach you choose.

The Importance of Line Shopping

Given that EV is theoretical and fragile, line shopping becomes even more critical. Since your real edge might vary slightly from your estimated EV, getting the best available price on every bet is crucial.

Example: You think your win probability for a bet is 55% at a -110 line. This gives you $5.00 of EV for every $100 bet.

But what if your theoretical edge was actually 54%? That drops your EV to approximately $3. The more your actual win probability differs from your estimate, the more risk you face.

However, if you shop for the best line and find -105 instead of -110, your EV stays around $5 even if you slightly overestimated your win probability.

Margins are slim in sports betting, but getting the best lines available adds up significantly over time. Better prices:

• Provide cushion when your theoretical edge is slightly off
• Mitigate losses when you unknowingly place -EV wagers
• Improve your long-term profitability
• Reduce exposure to negative variance

Even a few cents difference in odds can dramatically impact your results over hundreds or thousands of bets. This is why professional bettors always compare prices across multiple bookmakers before placing wagers.

Tools like FairOdds Terminal make line shopping effortless by automatically comparing odds across 200+ bookmakers in real-time, ensuring you always get the best available price.

Ready to find +EV bets automatically? Use FairOdds Terminal to identify positive expected value opportunities across 200+ bookmakers and build consistent profits through disciplined, data-driven betting.

Positive Expected Value FAQ