Vig (vigorish)
The sportsbook's commission, built into the odds, that makes both sides of a market pay less than a fair price.
Vig, short for vigorish and also called juice, is how a sportsbook makes money regardless of who wins. Instead of charging a fee, the book shades the odds on both sides so the payouts are slightly below fair value. It is the sports betting equivalent of the house edge.
Worked example
The classic two-way line is -110 on each side.
- You stake $110 to win $100 on either side.
- If one bettor takes each side, the book collects $220 and pays out $210 to the winner.
- It keeps $10, which is 10 / 220 = 4.55% of all money wagered.
The same answer comes from implied probability: -110 implies 110 / 210 = 52.38% per side, a total of 104.76%. Vig as a share of stakes is 4.76 / 104.76 = 4.55%.
Vig versus overround
The two numbers describe the same margin from different angles. Overround is the excess over 100% (4.76% here); vig is that excess as a share of the total book (4.55%). Both get bigger as the prices get worse for you.
Why it matters
At -110, a bettor needs to win 52.38% of bets just to break even. Shopping the same line at several books, including any reduced-juice lines a book runs, is the simplest way to pay less of it.