Bookmaker margin calculator
Enter the decimal odds of a 1X2 market. We work out how much the operator keeps and the implied probability of each outcome.
Worked example
For a match priced at 2.10, 3.40 and 3.60, add up the inverse of each price:
The sum is 0.048 above 1. Measured as the excess over 100% (S − 1), the margin is 4.8%. Measured as a share of total stakes ((S − 1) ÷ S), divide the excess by the sum:
The calculator highlights the second measure, 4.6%: what the operator keeps, on average, of every euro staked on the market. Both measures describe the same margin.
What is the bookmaker margin?
It's what the operator expects to keep, on average, on a market. It shows when the implied probabilities in the odds add up to more than 100%.
Why are there two measures?
The excess over 100% (S − 1) is the most quoted; the share of total stakes ((S − 1) ÷ S) says how much the operator keeps per euro staked. The calculator shows both and says which is which.
Does a low margin mean I'll win?
No. A lower margin only means the operator keeps less on average. The result of every bet stays uncertain.