Bookmaker Margin Calculator

How to use the bookmaker margin calculator

Pick your odds format (Decimal, Fractional or American), then enter the odds for every outcome in the market. A moneyline has two outcomes, a soccer match has three (home, draw, away), and an outright can have many, so use + Add outcome and the × button to match the market. The calculator shows the bookmaker margin, the hold and the total book, and next to each outcome it shows the no-vig fair odds with the margin stripped out. Decimal is the format Canadian sportsbooks show by default.

The terms in short

• Implied probability: the chance each price represents, found from the odds.
• Book sum: all the implied probabilities added up. A fair book would total 100%.
• Margin / overround / vig: how far the book sum sits above 100%. This is the built-in edge.
• Hold: the same edge expressed as a share of total stakes, which is what the book expects to keep.
• No-vig fair odds: the odds you would get if the margin were removed and the prices added to exactly 100%.

How the margin is calculated

Each price becomes an implied probability, they are summed, and the surplus over 100% is the margin:

• Implied probability100 ÷ decimal odds
• Book sumsum of all implied %
• Margin (overround)book sum − 100
• Holdmargin ÷ book sum
• No-vig fair %implied % ÷ book sum × 100
• No-vig fair decimaldecimal × (book sum ÷ 100)