Vig (or Juice) is the hidden commission sportsbooks charge. It is the mathematical advantage that ensures they profit regardless of the game's outcome.
Answer-first
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.