How to Use EV, No‑Vig, and Parlay Math to Win

Greg Kajewski
Sep 2
5 min read

Updated: 11 hours ago

Sports betting is an art, but it’s also undeniably a science. For those who shy away from math, this might sound daunting, but here’s the truth: you don’t need a degree in advanced mathematics to be sucessful. In fact, with a few core principles and formulas, anyone can learn how to identify profitable bets and win consistently over the long run.

This article delves into key sports betting concepts, such as expected value (EV), no-vig odds, and parlay math, providing step-by-step insights into how to use these tools effectively. Whether you’re a sharp bettor, a casual dabbler, or somewhere in between, these strategies can elevate your betting game while simultaneously fostering responsible and informed wagering habits.

Understanding the Core of Profitable Betting: Expected Value (EV)

At the heart of every successful sports betting strategy is one fundamental concept: expected value (EV). EV measures how much you can expect to win (or lose) on average for a given bet over the long run. It’s what separates bets that are mathematically profitable from those that are not.

Here's a straightforward example to help you grasp EV:

Imagine flipping a coin that is 55% likely to land on heads and 45% likely to land on tails.
If you bet $100 on heads at even odds (1:1 payout), 55% of the time you’ll win $100, and 45% of the time, you’ll lose $100.
The EV of this bet is calculated as:(0.55 × $100) - (0.45 × $100) = $10 expected profit per bet.

In this case, the "edge" of the bet is 10%, meaning that for every $100 wagered, you’re statistically likely to profit $10 over the long term.

Why EV Matters in Sports Betting

Sports betting is inherently uncertain. A "good" bet doesn’t guarantee a win in the short term, but over hundreds or thousands of bets, positive EV wagers will yield long-term profits. By contrast, bets with negative EV (e.g., betting on a coin toss with 50/50 odds but poor payouts) will erode your bankroll over time.

For bettors of all skill levels, consistently identifying and placing positive EV bets is the key to sustainable success.

No-Vig Odds: Decoding the True Value of a Bet

Sportsbooks make money by introducing a "vig" or "juice" into the odds they offer. This is essentially their built-in profit margin, which can obscure the true "fair" price of a bet. To find out whether a bet is truly profitable, bettors need to strip away this vig and calculate the no-vig odds - a process often referred to as "de-vigging."

How No-Vig Odds Work

Let’s break it down using a practical example:

A sportsbook offers odds of -187 for "Yes" and +157 for "No" on a UFC fight going the distance.
The spread (or juice) in this market is evident in the gap between these two values. To find the no-vig (fair) odds, we calculate the midpoint:(187 + 157) ÷ 2 = -172 (fair price for "Yes").

By comparing the no-vig line (-172) to the odds you’re being offered (e.g., -160), you can determine if the sportsbook is offering a favorable bet. In this case, -160 is better than the no-vig odds, making this a positive EV bet.

Why This Matters

Bettors have access to multiple sportsbooks, all of which offer slightly different odds. By comparing lines and calculating no-vig odds, you can exploit discrepancies and find bets where sportsbooks undervalue certain outcomes.

Think of it this way: in trading, your profit comes from buying low and selling high. In sports betting, your profit comes from betting on outcomes priced lower than their true value.

Parlay Math: The Truth About Combining Bets

Parlays are often labeled as "sucker bets" due to their high variance and low probability of success. However, this blanket statement is misleading. The profitability of parlays depends entirely on the quality of the individual bets included.

How Profitable Parlays Work

If each bet in a parlay has a positive EV, the combined parlay will also be profitable. For instance:

Let’s assume you place a three-leg parlay, and each leg has a 3% edge (positive EV).
Your overall ROI for the parlay would compound as 3% × 3% × 3% = 9%.

This means that, while the risk is higher (since all legs must win), the potential reward grows significantly. Conversely, if the bets have a negative EV (e.g., -5%), the losses compound, making parlays a fast track to losing money.

Key Consideration for Parlays

Most bettors lose money on parlays because they include bets without properly vetting their EV. To succeed, it’s essential to ensure that every leg of your parlay is mathematically profitable.

Odds Conversion: Deciphering Odds Formats

With the rise of new sportsbooks and platforms, odds are no longer presented in a single, uniform format. While traditional American odds (e.g., -110, +200) remain common, many sportsbooks have adopted decimal odds (e.g., 1.66x payout).

Converting Decimal Odds to American Odds

Decimal odds represent the total payout for a $1 bet, including your stake. For example:

A 1.66x payout means you’ll receive $1.66 for every $1 wagered ($0.66 profit).
To convert this to American odds, subtract your original stake:1.66 - 1 = 0.66 (profit). This corresponds to American odds of -151.

Once converted, you can compare these odds to other sportsbooks to identify value.

Why This Knowledge Is Essential

Understanding and converting odds formats ensures you aren’t confused or disadvantaged when comparing lines across platforms. Sharp bettors rely on accurate odds comparisons to find value and maximize their edge.

Key Takeaways

Expected Value (EV): The cornerstone of profitable sports betting. Focus on bets with positive EV to generate consistent long-term profits.
No-Vig Odds: Remove the sportsbook’s juice to uncover the true fair line. Compare these to the offered odds to find edge opportunities.
Parlay Math: Only include positive EV bets in your parlays to ensure profitability. Avoid stacking bets with negative ROI.
Odds Conversion: Learn how to convert between American and decimal odds for seamless comparisons across sportsbooks.
Long-Term Strategy: Profitability in betting is a marathon, not a sprint. Losing streaks are inevitable, but positive EV bets win out over the long run.

Final Thoughts

Sports betting is far more than a game of luck or fandom. It’s a skill-based endeavor rooted in math, logic, and discipline. By mastering the principles of EV, no-vig odds, and parlay math, you can shift the odds in your favor and approach betting with confidence.

Remember, successful bettors aren’t those who win every bet - they’re those who think critically, manage risk carefully, and consistently seek out value. With these insights, you’ll be well-equipped to join the small percentage of bettors who can consistently beat the books.

Source: "Sports Betting Math Explained (for Non-Math People)" - Alex Monahan, YouTube, Aug 12, 2025 - https://www.youtube.com/watch?v=QPOShjRzGsM

Use: Embedded for reference. Brief quotes used for commentary/review.