Vig (or Juice) is the hidden commission sportsbooks charge. It is the mathematical advantage that ensures they profit regardless of the game's outcome.
The short answer
Vigorish (Vig or Juice) is the fee a sportsbook charges for accepting a wager. It is built into the odds. For a standard spread bet, the odds are -110, meaning you must risk $110 to win $100. That extra $10 is the Vig.
1. How Vig Works
In a fair coin toss, odds would be +100/+100 (50% implied prob each).
Bookmakers skew this to -110/-110 (52.38% implied prob each). The total probability is 104.76%. That extra 4.76% is the Overround or profit margin.
2. Calculating Vig
THE MATH
Odds: -110 / -110
Step 1: Convert to probability: 52.38% + 52.38% = 104.76%
Step 2: Vig = 1 - (1 / 1.0476) = 4.54%
3. The Break-Even Hurdle
Because of Vig, you must win more than 50% of your bets to break even.
At -110 odds, the Break-Even Rate is 52.38%.
If you hit 53%, you are a profitable bettor.
FAQ
Is Vig the same at every sportsbook?
No. "Reduced Juice" books might offer -105 lines (lower vig), while high-fee books might charge -115 or worse on props.