Sportsbook Overround & No-Vig Calculator
Enter every outcome in decimal odds to calculate sportsbook overround and proportionally normalized probabilities. Includes an example and limitations.
Enter decimal odds for every mutually exclusive outcome in the same market. The calculator adds the implied probabilities to show overround, then normalizes them proportionally. That normalized estimate removes the displayed margin; it does not reveal an objectively true probability.
Calculate a complete market
Example: a two-way market at 1.91 and 1.91. Include all outcomes in the market.
What the numbers mean
For decimal odds, implied probability is 1 divided by the odds. At 1.91, that is about 52.36%. Two sides at 1.91 add to about 104.71%, so the market overround is about 4.71 percentage points.
Proportional normalization divides each raw implied probability by their total. In this equal-price example it returns 50% for each side. That is a calculation based on the displayed prices, not a guarantee about the real chance of either result.
Enter all outcomes from one market
Use odds from the same event and market, with one number for each mutually exclusive outcome. For a three-way soccer result, include home win, draw and away win. For a two-way market, include both sides.
Do not mix markets, combine prices from different events or leave out a possible result. An incomplete set changes the total and makes the overround misleading.
Limits of a no-vig estimate
This calculator removes the margin proportionally. Sportsbooks may distribute their margin unevenly, and odds can reflect news, market demand and different pricing models. The normalized result is one comparison method; it is not a sportsbook forecast or a recommendation to bet.
For the definitions and a worked pricing example, read how sportsbook overround works and what vig means.