Bookmaker Margin Calculator — a tool that automatically calculates how many percentage points a bookmaker builds into the odds. Bettors simply enter the odds for every possible outcome (for example, home win, draw, away win). The calculator converts those odds into implied probabilities, totals them, and shows:
- The sum of probabilities (usually greater than 100 %);
- The margin size expressed as a percentage.
Bookmaker margin is the hidden commission the bookmaker embeds in the odds. It guarantees the sportsbook a profit regardless of how the event ends.
No-Vig Calculation Example
A bookmaker offers the following odds for a football match:
- Team A to win — 2.00
- Draw X — 3.30
- Team B to win — 3.60
Convert the odds into probabilities:
- 1 / 2.00 = 50.00 %
- 1 / 3.30 ≈ 30.30 %
- 1 / 3.60 ≈ 27.78 %
Add the probabilities:
- 50.00 + 30.30 + 27.78 = 108.08 %
Calculate the margin:
- 108.08 % − 100 % = 8.08 %
The bookmaker’s margin is 8.08 %. This means the book embeds an 8.08 % “hidden commission” in the odds, ensuring a profit no matter what happens.
How to Use the Bookmaker-Margin Calculator
- Choose a sporting event. It can be a football or tennis match, or any other sport.
- Write down the odds for all main outcomes. For example: Team A 2.10, Draw 3.30, Team B 3.60.
- Open the margin calculator and enter each outcome’s odds in the corresponding fields.
- Click the calculate button. The tool automatically converts the odds to probabilities, adds them up, and shows how far the total exceeds 100 %.
- Read the result. The calculator displays what share of those odds is the bookmaker’s margin—presented as an exact percentage.