What Is Sportsbook Vig?
The vig — short for vigorish, also called juice or margin — is the fee a sportsbook builds into its prices. It is why both sides of a coin-flip market are usually -110 instead of +100.
The short answer
Convert both sides of a two-way market to implied probability and add them. A market with no margin totals exactly 100%. Anything above 100% is the sportsbook's margin. At -110/-110, each side implies 52.38%, a total of 104.76% — roughly 4.8% of built-in margin.
A worked example
Why it matters
The vig means you must win more than 50% of even-money bets just to break even — about 52.4% at -110. It is also why comparing prices across books matters: the same bet can carry very different margins at different sportsbooks. Note that vig is an estimated margin built into prices, not a guarantee of the book's realized profit on any game.
Try the math yourself
Vig CalculatorWant this checked on a real ticket?
EVScout applies this math to every leg of your parlay automatically — estimated fair odds, estimated EV, sportsbook margin, and correlation warnings.
Evaluate My Parlay