Sports Betting Odds Glossary: Vig, Implied Probability & More
Bikash Roy
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Bikash personally verifies every calculator against official standards (WHO, NIH, government data). Online research specialist, SEO strategist, and web developer with 10+ years building accurate digital tools.
Full bio →Sports betting odds carry more information than they look like at first glance. Here’s what the core terms mean for the no-vig calculator.
American Odds
The odds format standard in US sportsbooks, shown as a positive or negative number relative to a $100 bet. Negative odds (like -150) show how much you’d need to bet to win $100; positive odds (like +130) show how much you’d win on a $100 bet. See American vs. decimal vs. fractional odds for how to convert between formats.
Implied Probability
The probability of an outcome implied by a given set of odds, calculated directly from the odds themselves — before removing the bookmaker’s margin. Implied probability across all outcomes in a market always sums to more than 100%, because it bakes in the vig. See the no-vig calculator for the exact conversion formula from American odds.
Vig (Vigorish) / Juice
The sportsbook’s built-in profit margin, represented by how much a market’s total implied probability exceeds 100%. A standard -110/-110 line carries about 4.76% vig. Vig is how a book profits regardless of which side wins, as long as it takes roughly balanced action on both sides.
No-Vig (Fair) Odds
Odds recalculated after proportionally removing the vig from both sides’ implied probabilities — representing the market’s true assessed likelihood of each outcome with the book’s margin stripped out. The no-vig calculator computes this using the multiplicative method, the most common devig approach.
Devigging (Devig)
The process of removing vig from a set of odds to estimate fair, true probabilities. The multiplicative method (dividing each side’s implied probability by the total) is the simplest and most widely used approach; more advanced methods (Shin’s method, the power method) exist for markets with extreme favorites, where multiplicative devigging can slightly overcorrect.
Expected Value (EV)
The average amount a bet is expected to win or lose per dollar wagered over a large number of repetitions, calculated from the true (no-vig) probability compared against the odds actually being offered. A bet is “+EV” (positive expected value) when the offered odds pay out more than the true probability suggests is fair — see using no-vig odds to find value bets for how to identify this.
Line Shopping
Comparing the same bet’s odds across multiple sportsbooks before placing it, since different books price the same event slightly differently. Line shopping against a calculated no-vig fair-odds baseline is one of the most direct ways to find which book currently offers the best (least-vig, most favorable) price on a specific bet.
Two-Way Market
A betting market with exactly two possible outcomes (like a point spread or a moneyline in a two-team game), which is what the multiplicative no-vig method is designed for. Markets with three or more outcomes (like a soccer match’s win/draw/loss) require an adapted version of the same underlying math.
Ready to check the vig on a real line? Use the no-vig calculator, or see no-vig calculator examples for the math applied to different market types. Sports betting carries real financial risk — see the National Council on Problem Gambling if betting ever stops feeling like entertainment.