The vig (short for vigorish), also called juice or the margin, is the house's built-in fee. It is not charged separately. It is hidden inside the odds. Understanding the vig explains why the standard price is -110, why both sides of a game can show minus odds, and why beating the market over time is so difficult.
A simple example
Imagine a perfect coin flip. The fair price is even money: risk 100 to win 100 on either heads or tails.
Now imagine a bookmaker offers -110 on both sides. You risk 110 to win 100.
If one person picks heads for 110 and another picks tails for 110:
- The bookmaker takes in 220.
- The winner gets back 210 (110 stake + 100 profit).
- The bookmaker keeps 10.
It does not matter which side wins. That 10 out of 220 is about 4.5%. That is the vig.
How to calculate the vig
Convert each side to implied probability and add them up.
At -110 / -110:
- Each side: 110 ÷ 210 = 52.38%
- Total: 104.76%
The amount over 100% is called the overround. To get the house's theoretical cut per pick, use:
Vig = 1 − (1 ÷ total implied probability)
1 − (1 ÷ 1.0476) = 4.55%
Worked example on a moneyline
NBA game:
- Home -200 → 200 ÷ 300 = 66.67%
- Away +170 → 100 ÷ 270 = 37.04%
- Total = 103.71%
- Vig = 1 − (1 ÷ 1.0371) = 3.58%
A different listing for the same game:
- Home -190 → 65.52%
- Away +165 → 37.74%
- Total = 103.26% → vig ≈ 3.16%
The second listing is slightly better for players on both sides.
Why the vig matters so much
A 4.5% fee does not sound like much. But think about the break-even rate at -110: you need to win 52.4% of your picks just to stay even.
Over 100 picks of 110 each at -110:
- Win 50, lose 50: +5,000 − 5,500 = -500
- Win 52, lose 48: +5,200 − 5,280 = -80
- Win 53, lose 47: +5,300 − 5,170 = +130
- Win 55, lose 45: +5,500 − 4,950 = +550
Being "a bit better than a coin flip" is not enough. Most people, including people who follow sports closely, end up between 48% and 52% over a large sample. The vig makes that a losing range.
Where the vig is higher
The vig is not the same across every market.
- Main game lines (spreads, totals, moneylines on major leagues): usually the lowest margins.
- Player props and niche markets: typically higher.
- Futures (championship odds): often much higher, because there are many outcomes. Add up every team's implied probability in a futures market and you may see a total well above 100%, sometimes 20% to 40% over. See championship odds explained.
- Parlays: the vig compounds with each leg. See parlays explained.
Removing the vig to see "fair" odds
You can strip the vig out to estimate what the market really believes. Divide each implied probability by the total:
- Home: 66.67 ÷ 103.71 = 64.3%
- Away: 37.04 ÷ 103.71 = 35.7%
These are the no-vig probabilities. They are a useful starting point when you compare your own estimates against the market. Read more in implied probability.
The vig and line movement
Bookmakers sometimes adjust the price instead of the line. A spread might move from -3 (-110) to -3 (-120). The number stays the same, but the favorite becomes more expensive. This is called juicing a line. It usually tells you the market leans one way. See why betting lines move.
What the vig means for you
- Expect to lose over time. Even with good knowledge, the vig is a steady drag on results.
- Avoid high-margin markets if your goal is to measure your skill.
- Never treat wins as income. Short-term results are noisy, and the long-run math favors the house. See why sportsbooks win in the long run.
Learning without the cost
One of the best ways to see the vig in action is to track a long record of picks. On MockSport you can make free play-money picks on real lines, and watch how your token balance changes over dozens or hundreds of picks. Because there is no real money involved, the vig becomes a lesson rather than a cost. Start on the odds page or browse the learn hub.
FAQ
Why is the standard line -110?
It builds in a margin of about 4.5% on a 50/50 market. The house collects that margin over time regardless of which side wins.
Is the vig the same as a commission?
It works like one, but it is hidden in the price rather than charged separately. Some exchanges do charge an explicit commission instead.
How do I know if the vig is high?
Add up the implied probabilities of all outcomes. The further the total is above 100%, the higher the vig.