What Is Vig in Betting?

Vig — short for “vigorish,” and also called “juice” or “margin” — is the built-in commission inside betting odds. It’s the gap between what a market pays out and what it would pay if its implied probabilities added up to exactly 100%. On a −110/−110 two-way line, that gap is a 104.76% overround, or a 4.76% margin; removing it proportionally gives a no-vig estimate of 50.00% (2.00 in decimal odds) for each side, rather than what −110 implies on its own. A no-vig figure is the market’s own estimate with the margin stripped out — not the true probability, and other margin-removal methods can give slightly different answers.

How Vig Works

Every betting line is built from implied probabilities. Each price — American, decimal, or fractional — converts into a percentage chance of that outcome happening, according to the market. If you add up the implied probabilities of every outcome in a market, a “fair” market with no commission would sum to exactly 100%. Betting markets almost never do that. They’re priced above 100%, and that extra amount is the vig.

The total of all implied probabilities is called the overround. Subtract 100% from it and you get the margin. A second measure, the theoretical hold, is the share of all money wagered that the sportsbook keeps if stakes are spread so the total payout is the same whichever outcome wins: 1 − 1 ÷ overround (with the overround written as a decimal). Both are called “vig” or “juice” in everyday use, so it is worth knowing which one a source means. The hold a sportsbook actually makes depends on how the money really came in and on results.

This is why the prices on both sides of a two-way market look slightly worse than a fair coin flip: they are shaded so that, combined, they add up to more than 100%.

A Worked Example

Take a common US price for spreads and totals: −110 on both sides of a market.

• Each −110 price converts to an implied probability.
• Add both sides together and the market’s overround is 104.76%.
• Subtract 100% and the margin is 4.76%.
• Strip that margin out proportionally and the fair (market-implied, vig-free) probability on each side is 50.00% — a fair decimal price of 2.00.

In other words, a −110/−110 line is not really “50/50 odds with a small fee.” It’s priced so the combined probability is 104.76%, with the extra 4.76% representing the built-in margin. Measured as theoretical hold, the same line is 4.55% — the sportsbook’s cut of all money wagered if action is balanced. Reduced-juice lines exist too: −105/−105 cuts the margin to 2.44% and the hold to 2.38%.

Vig isn’t fixed, though — it moves with the odds. A moneyline market priced −150/+130 has a lower overround of 103.48%, a 3.48% margin. Converting those prices to fair, no-vig American odds gives −138/+138 — tighter than the quoted −150/+130, but not identical, because the margin has been removed.

Vig also isn’t limited to two-way markets. Add more outcomes and the math still works the same way, just split across more prices.

Vig Across Different Market Types

Here’s how the examples above compare, showing how margin and fair pricing shift depending on the market:

Market	Odds Quoted	Overround	Margin	Theoretical hold	Fair (no-vig) price or probability
Two-way, even juice	−110 / −110	104.76%	4.76%	4.55%	50.00% each (2.00 decimal)
Two-way, uneven juice	−150 / +130	103.48%	3.48%	3.36%	−138 / +138
Three-way (soccer)	2.50 / 3.20 / 3.00	104.58%	4.58%	4.38%	38.25% / 29.88% / 31.87%

Notice the three-way soccer market: three decimal prices (2.50, 3.20, 3.00) covering a home win, draw, and away win. Converting each to implied probability and adding them together produces a 104.58% overround — a 4.58% margin — and fair probabilities of 38.25%, 29.88%, and 31.87% once that margin is stripped out. More outcomes doesn’t automatically mean more vig; it depends entirely on how the individual prices are set.

Why Vig Matters for Expected Value

Vig is one reason a price’s implied probability can’t be read as the true chance of an outcome — and even after removing it, the no-vig figure is still only the market’s estimate. That distinction matters when thinking about expected value (EV) — the average result you’d expect from a bet if you could repeat it many times.

For example, if the true, fair chance of an outcome is even money (50%), but a price of +105 is available on it, that price implies slightly better payout odds than the fair line suggests. The expected value of taking +105 against a fair 50% outcome works out to 2.50%. That’s a useful illustration of how EV calculations work in theory — comparing a quoted price against a true probability — not a claim about how often any specific bet wins. Figuring out whether a real-world price has positive EV requires knowing the true probability, which is rarely something anyone can be certain of.

This is also why removing the vig matters before comparing markets or analyzing a bet. If you evaluate a bet using the market’s own implied probability (which already includes the margin), you’re measuring against a number that was never meant to be “fair” in the first place.

Common Mistakes

• Treating −110 as “50/50 for a small fee.” The fair probability behind −110/−110 is 50.00% only after the 4.76% margin is removed; at the quoted price, each side implies more than a coin flip, which is exactly where the sportsbook’s edge sits.
• Mixing up margin and hold. 4.76% and 4.55% describe the same −110/−110 line; one is the overround minus 100%, the other is the theoretical hold. Compare like with like.
• Assuming vig is the same everywhere. A −150/+130 line (3.48% margin) and a −110/−110 line (4.76% margin) carry different amounts of built-in commission, and three-way markets add another layer of complexity.
• Mixing up price shopping and probability estimates. For the same selection under the same rules, the higher decimal price simply pays more — no vig removal needed. Removing the margin matters when you want the market’s probability estimate, for example to judge expected value.
• Confusing positive EV with a guaranteed outcome. A 2.50% edge, like in the +105 example above, describes a long-run average, not a promise about any individual bet.
• Forgetting that vig applies to every market type, including totals, moneylines, and multi-outcome markets like three-way soccer — not just spreads.

Using a Vig Calculator

Manually converting odds to implied probability, summing them, and normalizing back to fair prices is doable with a formula, but it’s easy to make arithmetic mistakes, especially with American odds or three-way markets. Our vig calculator does this automatically — enter every quoted price and it returns the theoretical hold, the margin, the overround and the fair odds for each side, the same way the table above was produced. To check whether a specific price is worth taking against the fair line, use the no-vig calculator or the EV calculator.

Understanding vig is also a useful foundation before digging into how odds formats and conversions work more broadly, since every odds format is just a different way of expressing the same implied probability.

Vig is simply math built into every price — understanding it won’t change the odds, but it helps you read them more accurately. Always gamble responsibly, and only bet what you can afford to lose (18+/21+ where applicable).