What is Betting Edge? A Complete Guide to Finding Value

In sports betting, the difference between long-term winners and losers comes down to one concept: edge. Understanding what edge is and how to find it is the foundation of profitable betting. This guide will teach you everything you need to know about betting edge and expected value.

What is Betting Edge?

Betting edge is the mathematical advantage you have over the sportsbook on a particular wager. When you have positive edge, you're expected to profit over time. When you have negative edge (which is most bets), the sportsbook has the advantage.

Think of it like a casino. The house edge on roulette means that over thousands of spins, the casino will profit. But in sports betting, the lines aren't always perfectly efficient. When sportsbooks misprice a line, sharp bettors can find positive edge opportunities.

Edge is typically expressed as a percentage. A 5% edge means that for every $100 you bet, you expect to profit $5 on average. While any single bet might win or lose, edge compounds over hundreds of bets to produce consistent profits.

Understanding Expected Value (EV)

Expected Value (EV) is the mathematical formula for calculating edge. It represents the average amount you expect to win or lose per bet if you made the same bet thousands of times.

The formula is straightforward:

EV = (Probability of Winning x Amount Won) - (Probability of Losing x Amount Lost)

A positive EV (+EV) bet has edge in your favor. A negative EV (-EV) bet favors the sportsbook. Professional bettors only make +EV bets, even though individual bets may lose.

For example, imagine a coin flip where you win $110 on heads but lose $100 on tails. The EV would be:

(0.50 x $110) - (0.50 x $100) = $55 - $50 = +$5 EV

This means you'd expect to profit $5 per bet on average. Even though you'll lose 50% of the time, the payouts make it a winning proposition long-term.

How to Calculate Expected Value

To calculate EV for a sports bet, you need two things: the true probability of an outcome and the odds you're getting.

Step 1: Convert odds to implied probability

American odds can be converted to implied probability:

• For negative odds: Implied Probability = |Odds| / (|Odds| + 100)
• For positive odds: Implied Probability = 100 / (Odds + 100)

For example, -150 odds imply a 60% probability (150/250 = 0.60). +150 odds imply a 40% probability (100/250 = 0.40).

Step 2: Determine true probability

This is the hard part. True probability is what you believe the actual chance of winning is, based on your analysis. If the true probability exceeds the implied probability, you have edge.

Step 3: Calculate EV

If you believe a team has a 55% chance to cover a spread at -110 odds:

• Win payout on $110 bet = $100
• EV = (0.55 x $100) - (0.45 x $110) = $55 - $49.50 = +$5.50

That's a 5% edge on your bet ($5.50 / $110).

How to Find Betting Edge

There are several proven ways to find edge in sports betting:

1. Line Shopping

Different sportsbooks offer different odds on the same event. By comparing lines across multiple books, you can always bet the best available price. Even half a point on a spread or slightly better moneyline odds adds up significantly over time.

2. Market Inefficiencies

Sportsbooks aren't perfect. They misprice lines for various reasons: overreaction to public perception, slow to adjust to news, or limited information on smaller markets. Finding these mispricings before they're corrected is a source of edge.

3. Steam Moves

When sharp bettors (professionals with proven track records) hammer a line, it moves quickly across the market. Getting in before or during these steam moves can capture edge before the line settles at a more efficient price.

4. Closing Line Value

The closing line (the final odds before an event starts) is generally the most accurate. Consistently beating the closing line indicates you're finding edge. Learn more about CLV in our dedicated article.

5. Props and Derivatives

Prop bets and derivative markets often have softer lines than major markets like spreads and moneylines. Sportsbooks spend less time refining these odds, creating opportunities for informed bettors.

How Prop Monkey Finds Edge

At Prop Monkey, we automate the process of finding edge so you don't have to do it manually.

Multi-Book Aggregation

We pull odds from every major sportsbook with frequent updates. This lets us identify the sharpest line for any bet and calculate how much edge each sportsbook offers compared to the market.

No-Vig True Odds

We remove the vig (the sportsbook's built-in margin) from odds to calculate true market probabilities. This reveals which lines are mispriced and by how much.

Edge Quantification

Every pick shows you the exact edge percentage. We only surface bets with meaningful positive expected value, so you're always betting with a mathematical advantage.

Kelly Criterion Sizing

Finding edge is only half the battle. We also calculate optimal bet sizes using the Kelly Criterion, helping you maximize long-term bankroll growth without overexposing yourself on any single bet. Learn about the Kelly Criterion.

Ready to stop guessing and start betting with edge? Try Prop Monkey free.

Common Mistakes to Avoid

Chasing Losses

Edge doesn't guarantee wins. You'll have losing streaks even with positive EV bets. Chasing losses by increasing bet sizes or making -EV bets destroys your edge advantage.

Ignoring Line Movement

A bet that had edge this morning might not have edge now. Lines move as information comes in and money is wagered. Always check current odds before betting.

Overconfidence in Your Edge

Be realistic about your edge estimates. Even a 2-3% edge is valuable over time. Don't oversize bets based on inflated edge calculations.

Focusing on Win Rate

A 60% win rate on -200 favorites loses money. A 45% win rate on +200 underdogs is highly profitable. What matters is expected value, not win percentage.

Putting It All Together

Betting edge is the foundation of profitable sports betting. By understanding expected value and focusing on +EV opportunities, you can turn sports betting from gambling into investing.

The key principles to remember:

• Edge is your mathematical advantage over the sportsbook
• Expected Value (EV) quantifies that edge
• Positive EV bets profit long-term, even with losing streaks
• Line shopping and market analysis help you find edge
• Bet sizing matters as much as bet selection

Finding edge manually is time-consuming, which is why we built Prop Monkey. We do the math so you can focus on placing winning bets.