What Is the Vig in Sports Betting? How Bookmakers Make Money
The vigorish, commonly called "vig" or "juice," is the bookmaker's built-in commission on every bet. It is the primary way sportsbooks generate profit regardless of the outcome. Understanding the vig is essential for any bettor because it directly impacts your long-term profitability. The lower the vig, the less you are paying in hidden costs on every wager.
How the Vig Works
In a perfectly fair market for a coin flip, both sides would be priced at 2.00 (even money). The implied probabilities would be 50% + 50% = 100%. However, a sportsbook might price both sides at 1.91 instead. The implied probabilities become 52.36% + 52.36% = 104.72%. That extra 4.72% above 100% is the overround, and it represents the bookmaker's margin. No matter which side wins, the sportsbook collects slightly more in bets than it pays out.
Calculating the Vig
To calculate the vig, sum the implied probabilities of all outcomes. Implied probability = 1 / decimal odds. For a two-way market with odds of 1.90 and 2.00: implied probabilities are 52.63% and 50.00%, totaling 102.63%. The vig is 102.63% - 100% = 2.63%. For three-way markets (common in soccer with home/draw/away), the vig tends to be higher because bookmakers can spread their margin across more outcomes.
What Is a Good Vig?
The vig varies significantly across sportsbooks and bet types. Sharp sportsbooks like Pinnacle typically offer vig between 2% and 4% on major markets. Recreational sportsbooks might charge 5% to 8% or even higher on prop bets and exotic markets. Prediction markets like Polymarket often have very low effective vig since they operate as peer-to-peer exchanges. The best bettors shop across platforms to find the lowest vig, because even a 1% reduction in vig adds up to significant savings over thousands of bets.
Fair Odds vs. Market Odds
"Fair odds" are what the odds would be if the bookmaker took zero margin. To calculate fair odds from market odds, use the multiplicative method: divide each outcome's implied probability by the total implied probability sum, then convert back to decimal odds. For example, with market odds of 1.90 (52.63%) and 2.00 (50.00%), the total is 102.63%. Fair probabilities are 52.63/102.63 = 51.28% and 50.00/102.63 = 48.72%. Fair odds are 1.95 and 2.05 respectively.
Why the Vig Matters for Your Bottom Line
Think of the vig as a tax on every bet. If you are betting at a 5% vig book versus a 2% vig book, that 3% difference compounds dramatically. Over 1,000 bets at $100 each, the higher-vig book costs you approximately $3,000 more in margin. For a bettor with a genuine 3% edge, the difference between a 2% vig book and a 5% vig book is the difference between being profitable and being unprofitable.
The Vig in Different Markets
The vig is not uniform across all bet types. Major market lines like NFL point spreads and NBA moneylines typically have the lowest vig at sharp books, often under 3%. Player prop bets usually carry higher vig, sometimes 6% to 10%, because the market is less efficient and the bookmaker has more pricing power. Live betting markets tend to have wider margins because the bookmaker needs to compensate for the speed of information flow and the risk of being picked off by sharp bettors.
Comparing Vig Across Platforms
OddsBridge helps you compare the effective vig across sportsbooks and prediction markets for the same event. By stripping out the margin and looking at fair probabilities, you can see which platform is offering you the best deal on each outcome. Sometimes a prediction market prices one side more favorably while a sportsbook offers better value on the other side. Using our vig calculator alongside the odds comparison table gives you a complete picture of where your money goes furthest.
Reducing Your Vig Exposure
The most effective way to reduce vig is to bet at the sharpest available books. Pinnacle, for example, is known for thin margins on major markets. Betting exchanges like Betfair charge a commission on net winnings rather than building vig into the odds, which often works out cheaper for frequent bettors. Prediction markets offer another avenue with low effective fees. Line shopping across multiple platforms before placing any bet is the single easiest way to improve your expected returns.