Market Prices & Execution
No-Vig Probability Explained: Normalize Both Sides of a Market
No-vig probability rescales the implied percentages from every side of one market so they total 100%. It is a market-price normalization, not a forecast.
Direct answer
No-vig probability removes the mathematical overround from all sides of one market by rescaling their price-implied percentages to total 100%. It describes those selected prices without their combined margin. It does not reveal a guaranteed or objectively true probability.
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Side A: -120 → 54.55% raw implied probability
Side B: +100 → 50.00% raw implied probability
Combined: 104.55%
Normalized: 52.17% and 47.83%
For proportional normalization, divide each raw percentage by the combined 104.55%. Side A becomes 54.55 ÷ 104.55 = 52.17%. Side B becomes 50 ÷ 104.55 = 47.83%.
- Book prices
- Side A -120 · Side B +100
- Raw implied percentages
- 54.55% + 50.00% = 104.55%
- No-vig normalization
- 52.17% · 47.83% = 100.00%
Hypothetical two-way market using proportional normalization. A no-vig result describes the selected prices; it is not a guarantee or a true-probability measurement.
Why both sides are required
A single American price can be converted to raw implied probability, but it cannot show the full market margin. No-vig normalization needs every mutually exclusive side from the same sportsbook, market, selection set and observation time.
Common mistake
Do not call the normalized result the true chance of an outcome. The result inherits the information and limitations of the chosen quotes. Different sportsbooks, timestamps or normalization methods can produce different estimates.
Why it matters
The calculation separates two related ideas: the price attached to one side and the total margin embedded across the market. That makes it easier to compare price structure without confusing a sportsbook quote with a forecast.
Learn next
Moneyline Implied Probability explains the first conversion. What Is Vig or Juice explains why two sides can add above 100%. Why Sportsbook Prices Differ shows why the same market can produce different inputs across books.