This tool calculates the bookmaker margin (overround) and vigorish (vig) for a set of entered odds. Arbitrage opportunities are highlighted if they exist.
To use the calculator, select your preferred odds format, input the odds for as many selections as you need, then press “Calculate”.
What Are Bookmaker Margins?
The bookmaker margin, also known as the overround, the cut or the take, is the hidden amount charged by a bookmaker for accepting a wager.
The bookmaker margin is a measure of the bookmaker’s profit margin for an event and is a hidden transaction cost for punters. This profit is how bookmakers finance their services but bookmakers vary in the margins they apply. From a punter’s perspective, the lower the margin, the better.
By joining more than one bookmaker, punters can lower the effective margins by shopping around for odds. In some circumstances the combined bookmaker margin can be negative, which indicates an arbitrage opportunity exists.
Unfortunately there are conflicting definitions of bookmaker margin and vigorish. Even on Wikipedia the explanation of how to calculate vigorish depends on which article you visit. This calculator uses the definition of bookmaker margin (overround) as used in the Mathematics of bookmaking Wikipedia article and the definition of vigorish as used in the Vigorish Wikipedia article.
Bookmaker Margin Calculator
Select your preferred odds type from the drop down list: