Bookmaker Margin Calculator: Overround & No-Vig Odds
Enter the odds for every outcome in a market. The calculator shows each implied probability, the book percentage, overround, hold and payout, then removes the margin to give fair probabilities and no-vig odds using the proportional, power or Shin method.
Free bookmaker margin calculator: enter the odds for every outcome to get the overround, margin, payout and fair no-vig odds and probabilities. 2-way, 3-way or more.
Frequently asked questions
How do you calculate bookmaker margin?
Convert every outcome's decimal odds to an implied probability (1 / odds) and add them up. The total is the book. Anything above 100% is the overround. For 2.10, 3.40 and 3.60 the implied probabilities are 47.62%, 29.41% and 27.78%, so the book is 104.81% and the overround is 4.81%.
What is the difference between overround and margin?
Overround is the book minus 100%, so 4.81% in the example above. The hold (often called the true margin) is the share of a balanced book the bookmaker keeps: 1 - 1 / book, or 4.59% in the same example. Payout is 1 / book, 95.41%. Many sites call the overround the margin, so check which one a figure means.
What is a typical bookmaker margin on football?
In the 2024/25 top five European leagues, Bet365's pre-match 1X2 odds averaged a 5.56% overround and Pinnacle's 3.60% (1,752 matches, odds from football-data.co.uk). Over/under 2.5 goals averaged 4.86% at Bet365 and 3.56% at Pinnacle. Niche markets such as corners, cards and player props usually carry more.
What are no-vig (fair) odds?
No-vig odds are the prices with the bookmaker's margin taken out, so the implied probabilities add up to exactly 100%. They are an estimate of what the market thinks each outcome's real chance is. Compare them with your own probability, or with another bookmaker's price, to judge value.
Which method should I use to remove the vig?
The proportional method divides each implied probability by the book. It is simple and standard, but it assumes the margin is spread evenly. Bookmakers tend to load more margin onto longshots, so the power and Shin methods, which take more margin off long prices, usually fit results better when one side is a big favourite. For two near-even outcomes, all three give almost the same answer.
What does it mean if the book is below 100%?
Implied probabilities that add up to less than 100% mean that backing every outcome in the right proportions would guarantee a profit. That usually happens only when you combine the best prices from different bookmakers, and the gap tends to close quickly. Check that the prices are live and that the bookmakers settle the market the same way.