No Vig Probability: How to Remove the Bookmaker Margin
Learn how to calculate no vig probability from betting odds, remove the bookmaker margin, and interpret fair market probabilities for two-way and multi-way markets.
No vig probability is the implied probability of an outcome after removing the bookmaker’s margin, also called the vig, juice, or overround. It estimates the market’s fair probability before the built-in sportsbook profit is added.
For example, if a two-outcome market gives one side a raw implied probability of 60% and the other 50%, the total is 110%. The extra 10 percentage points represent the overround. Normalising those figures produces no vig probabilities of approximately 54.55% and 45.45%.
What no vig probability means
Decimal odds can be converted into raw implied probability with this formula:
Raw implied probability = 1 ÷ decimal odds
Those raw probabilities usually add up to more than 100% because the sportsbook builds a margin into the prices. No vig probability adjusts each outcome so that the probabilities add up to exactly 100%.
The calculation is useful for estimating a market’s consensus view without treating the bookmaker’s margin as part of the actual chance of each outcome. It does not reveal the true probability with certainty. It is a price-based estimate derived from the available odds.
How to calculate no vig probability
First convert every selection’s decimal odds into an implied probability. Then add the raw probabilities together and divide each individual probability by that total.
No vig probability = raw implied probability ÷ sum of all raw implied probabilities
Two-outcome example
Suppose a tennis match has these decimal odds:
- Player A: 1.70
- Player B: 2.20
The raw implied probabilities are:
- Player A: 1 ÷ 1.70 = 58.82%
- Player B: 1 ÷ 2.20 = 45.45%
The implied probability total is 104.27%, so the estimated overround is 4.27%.
To remove the vig:
- Player A: 58.82 ÷ 104.27 = 56.42%
- Player B: 45.45 ÷ 104.27 = 43.58%
The no vig probabilities total 100%. The corresponding fair decimal odds would be approximately 1.77 for Player A and 2.29 for Player B.
No vig probability for three-way markets
The same method applies to football 1X2 markets, where the possible outcomes are home win, draw, and away win. Convert all three prices into raw implied probabilities, add them, and divide each result by the total.
For example, odds of 2.00, 3.40, and 4.00 produce raw implied probabilities of 50.00%, 29.41%, and 25.00%. Their total is 104.41%. After normalisation, the no vig estimates are approximately:
- Home win: 47.89%
- Draw: 28.17%
- Away win: 23.94%
This approach is also suitable for totals, player props, outright markets, and other markets with more than two selections, provided all relevant outcomes are included and the prices refer to the same market.
Why removing the vig matters
Comparing raw implied probabilities with no vig probabilities shows how much of the price reflects the bookmaker margin. It can also help compare markets offered by different sportsbooks, since a lower-overround market generally gives a cleaner view of the market’s underlying pricing.
Traders and bettors may use no vig odds to estimate a market-implied fair price, compare a personal probability forecast with the market, or identify how much margin is present in a betting market. Any value assessment should still account for limits, changing prices, market liquidity, and the assumptions behind the probability estimate.
Limitations of the calculation
Simple proportional normalisation is widely used, but it is an approximation. It assumes the bookmaker margin is distributed across outcomes in proportion to their raw implied probabilities. That may not reflect how a sportsbook actually sets prices.
Long-shot outcomes can carry a larger relative markup than favourites, particularly in some outright and multi-runner markets. In those cases, alternative margin-removal methods may produce different fair probabilities. The result can also be distorted by stale odds, low liquidity, limits, or prices copied from another market.
No vig probability should therefore be treated as a useful market estimate rather than an objective, guaranteed probability. Checking several reputable prices and using the same calculation consistently usually gives a more informative comparison.
Quick formula reference
- Raw implied probability: 1 ÷ decimal odds
- Overround: sum of raw implied probabilities − 100%
- No vig probability: raw implied probability ÷ total raw implied probabilities
- Fair decimal odds: 1 ÷ no vig probability
All probabilities should be expressed in the same format during the calculation. Convert percentages to decimals when using a calculator, then multiply the final result by 100 to display a percentage.
