What Is the Vig in Sports Betting?

Every sportsbook needs a way to earn money whichever team wins. It does not send an invoice; it builds the charge into the odds. That charge is called the vig, short for vigorish, and it also goes by juice, margin or overround depending on who is talking. Once you can see it, you will notice it on every betting board, and it explains why sports betting costs money over time even for people who know their sport.

Like the rest of the site, this explainer is meant for readers of 18 and above. It describes how pricing works; it is not advice to bet.

The classic example with two bettors

The easiest way to picture the vig is a game in which both sides are priced at -110, the familiar American line on spreads and totals. At -110 you risk $110 to win $100.

Imagine two customers, one on each side, each staking $110. The book now holds $220. When the game ends, one ticket wins and is paid $210: the $110 stake back plus $100 profit. The other ticket loses. The book keeps the remaining $10 regardless of the score. Measured against the $220 taken in, that is about 4.5% of everything staked, and it is earned without the book needing to know who would win.

Real books rarely see perfectly balanced money, so their actual result on a given game swings around. Across thousands of markets, though, that built-in slice is what keeps them in business.

What the vig means for the bettor

Turn the same -110 price around and ask how often a bettor needs to be right just to finish level. You risk 110 to collect 210 in total, so the break-even rate is 110 divided by 210, a little under 52.4%. Being right exactly half the time, which already takes real skill or luck against a well-set line, still loses money slowly. The vig is the gap between those two figures.

Measuring the vig on any market

You can check the margin yourself with three steps:

1. Convert each price into the probability it implies. For decimal odds, divide 1 by the price. For a minus American price, divide the number by itself plus 100. For a plus price, take 100 and divide it by the sum of 100 and the number shown.
2. Add up the probabilities for every possible outcome in the market.
3. Subtract 100%. Whatever is left over is the overround.

The figures in the table are examples built for this article, not prices from any particular operator. You may notice that the overround (about 4.8% on the first row) and the share the book keeps from balanced action (about 4.5%) are not identical; they are two ways of describing the same cushion from different starting points.

Stripping the vig out of a price

Sometimes it is useful to know what a price would look like without the margin. Take the moneyline row: -150 implies 60%, +130 implies about 43.5%, and together they reach about 103.5%. Divide each figure by that total and you get roughly 58% and 42%, which now add up to exactly 100%. Those are the book's own estimates with its fee removed. They are still only estimates; nobody knows the true chance of a sporting result.

Where the vig tends to be larger

• Markets with many outcomes. Futures, first scorers and long lists of options leave more room for a margin to hide.
• Combined tickets. In a parlay or a teaser the margin of each leg is multiplied into the next, so the cost grows with every selection. Our guide to teaser bets shows how that plays out.
• Niche events. Lower-profile leagues and props are harder to price, and books usually protect themselves with a wider cushion.

Betting exchanges handle this differently: rather than building a margin into odds, they usually charge a commission on winnings. The fee is still there; it is just collected in another way.

Why it is worth knowing

Sports betting has changed a great deal over the years, from bookmakers' counters to apps, a story told in our history of sports betting. The vig is the part that has not changed. Understanding it will not make anyone a winning bettor, but it does turn odds from a vague promise into a clear price. Bet only if you are of legal age, check the rules where you live because sports wagering is restricted in many places, and treat the money you stake as the cost of entertainment rather than an investment.