What is the vig?
The vig (short for vigorish, also called juice) is the margin a sportsbook builds into its prices. Instead of paying the odds a fair coin flip deserves, the book pays slightly less on every outcome, so the probabilities implied by its prices add up to more than 100%.
The standard example is a point spread priced at -110 on both sides. You risk $110 to win $100, which implies a 52.38% chance for each side. Together the two sides total 104.76%. A fair two-way market would total exactly 100%, and the extra 4.76% is the vig.
A no-vig calculator removes that margin. What remains is the no-vig probability of each outcome, also called the fair implied probability, and the fair odds that match it.
How to use the no-vig calculator
- Choose the Odds format: American (the default), decimal or fractional.
- Enter the odds for every outcome of one market: both sides of a spread or total, both teams on a moneyline, or home, draw and away in a three-way market. Names are optional and appear in the results and copied text.
- Use Add outcome for markets with more than two outcomes, up to 10. Remove any row you don't need.
- Read the no-vig probability and fair odds for each outcome, then the market summary: total implied probability, overround and theoretical hold. Copy result copies everything as plain text.
Results update as you type, and switching the odds format rewrites the prices you've entered in the new format (decimal odds to at most four decimal places). Everything is calculated in your browser.
For an accurate result:
- Include every outcome. Leaving out the draw in a soccer market, for example, makes the total look smaller than it is.
- Use one sportsbook at one moment. Mixing prices from different books or times describes no real market, and the margin you see won't belong to anyone.
- Keep to one market. A spread price and a moneyline price are different markets, even for the same game.
- Spreads and totals that can push are still treated as two outcomes. The calculator doesn't estimate the chance of a push.
How no-vig odds are calculated
The calculator uses proportional normalization, also called the multiplicative method: it scales every implied probability by the same factor so that the market totals exactly 100%.
Step 1: Convert the odds to implied probabilities
Each price implies a probability. These are the standard conversions:
| Odds format | Implied probability | Example |
|---|---|---|
| American, negative (-A) | A ÷ (A + 100) | -150 → 60.00% |
| American, positive (+A) | 100 ÷ (A + 100) | +130 → 43.48% |
| Decimal (D) | 1 ÷ D | 2.50 → 40.00% |
| Fractional (n/d) | d ÷ (n + d) | 5/2 → 28.57% |
American odds of +100 and -100 both mean even money (decimal 2.00, fractional 1/1). Odds between -100 and +100 don't exist, and 0 isn't a valid price.
Step 2: Add up the market
Add the implied probabilities of all the outcomes. The result is the total implied probability, sometimes called the book: total = p₁ + p₂ + … + pₙ.
Step 3: Remove the margin
Divide each implied probability by the total: no-vig probability = implied probability ÷ total. The no-vig probabilities always add up to 100% (displayed values can differ by 0.01% because of rounding).
Step 4: Convert back to fair odds
- Fair decimal odds:
1 ÷ no-vig probability - Fair American odds, favorite (no-vig probability above 50%):
−100 × q ÷ (1 − q) - Fair American odds, underdog (50% or less):
+100 × (1 − q) ÷ q
Here q is the no-vig probability. The calculator rounds fair American odds to the nearest whole number and fair decimal odds to three decimal places, and keeps full precision in between.
Overround vs theoretical hold
People call two different numbers "the vig", so the calculator shows both, with names that keep them apart:
- Overround:
total − 1, how far the total implied probability is above 100%. - Theoretical hold:
1 − 1 ÷ total, the share of all money staked that the book keeps if bettors' stakes are balanced in line with its prices.
For -110 on both sides, the overround is 4.76% and the theoretical hold is 4.55%. The hold is easy to check with money: if one bettor risks $110 on each side, the book takes in $220 and pays the winner $210, keeping $10, which is 4.55% of $220.
The hold is always a little smaller than the overround, and both shrink as prices improve: at -105 on both sides, the overround is 2.44% and the hold 2.38%. When you compare the margin of different markets or sportsbooks, compare the same measure.
Worked examples
Even line: -110 / -110
Each side implies 52.38%, for a total of 104.76%. Dividing 52.38% by 104.76% gives a no-vig probability of 50.00% for each side, so the fair price is +100 (decimal 2.00). Overround 4.76%, theoretical hold 4.55%.
Favorite and underdog: -150 / +130
The favorite at -150 implies 60.00% and the underdog at +130 implies 43.48%, a total of 103.48%. Normalized, the favorite's no-vig probability is 57.98% (fair odds -138, decimal 1.725) and the underdog's is 42.02% (fair odds +138, decimal 2.38). Overround 3.48%, theoretical hold 3.36%.
In a two-way market, fair American odds come out as mirror images, here -138 and +138.
Three-way soccer market
A match priced with the home team at +145, the draw at +240 and the away team at +190 has three outcomes, and all three must be entered:
| Outcome | Odds | Implied probability | No-vig probability | Fair odds (decimal) |
|---|---|---|---|---|
| Home | +145 | 40.82% | 38.98% | +157 (2.565) |
| Draw | +240 | 29.41% | 28.09% | +256 (3.56) |
| Away | +190 | 34.48% | 32.93% | +204 (3.037) |
The total implied probability is 104.71%: overround 4.71%, theoretical hold 4.50%.
When prices total 100% or less
If the implied probabilities total exactly 100%, the market has no margin to remove, and the no-vig probabilities equal the implied ones. That's the case for +100 on both sides.
A total below 100% is an underround, and there is no positive bookmaker margin to remove. For example, -105 at one sportsbook and +110 at another total 98.84%. The calculator labels the market Underround and still divides each implied probability by the total, but shows the results as normalized probabilities and normalized fair odds, for comparison only: 51.82% (-108) and 48.18% (+108). Normalizing raises each probability here, and the overround and theoretical hold are negative (-1.16% and -1.18%). A single book rarely prices one market below 100%, so a total like this usually means the prices come from different books or times, or an outcome is missing.
No-vig probability is not a prediction
Removing the vig doesn't reveal how likely an outcome really is. A no-vig probability is the sportsbook's price with its margin taken out under one assumption: that the margin is spread across the outcomes in proportion to their probabilities. That makes it a useful reference price, and a common way to compare prices across sportsbooks, but not an independent forecast.
Two things limit it:
- The prices can be wrong. A no-vig probability is only as good as the market it comes from.
- Margins aren't always spread proportionally. Research has found that bookmakers often build more margin into longshots than into favorites, the favorite-longshot bias. Proportional normalization ignores this, so it can overstate an underdog's fair chance a little.
That's why this page avoids calling the result a "true probability". No-vig odds are a mathematical transformation of quoted odds, not betting advice.
Other ways to remove the vig
Proportional normalization is the standard method and the one most no-vig calculators use. Other methods divide the margin differently:
- Additive: subtracts the same amount from every outcome's implied probability. It can produce negative probabilities for big longshots.
- Power: raises each implied probability to the same power, chosen so the results sum to 100%. It takes more margin out of longshots than proportional normalization does.
- Shin's method: based on a model of informed betting by Hyun Song Shin. In a two-outcome market it gives the same result as the additive method.
In a 2017 comparison across three large bookmaker datasets, Clarke, Kovalchik and Ingram found that the power method outperformed proportional normalization and performed at least as well as Shin's method. When every outcome has the same price, all these methods agree. The further apart the prices, the more their fair odds can differ, so this calculator's results are specific to the proportional method.
Methodology and sources
The calculator reads each price as an exact ratio, so the odds you enter are never rounded before the calculation. It computes implied probabilities, the market total, the no-vig probabilities and fair odds at full precision, and rounds only for display. Our methodology explains how calculators are built and tested, and the calculator disclaimer explains their limits. This calculator shows the mathematics of quoted odds; it doesn't recommend bets. If gambling stops being fun, the National Council on Problem Gambling offers confidential help at 1-800-MY-RESET.