Margin Calculator
Calculate a bookmaker's margin.
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Bookmaker's make their money by including a betting marging in the odds. By inflating the implied probability of an outcome, they decrease the odds, which means you make less money when you win. The margin is, in essence, the difference between the real probabilities of an event and the odds offered by the bookmaker.
If you are serious about making a profit, you should keep an eye on the best odds and lowest margins offered by bookmaker's. Our Margin Calculator makes it easy to find out how much you're being charged! It also tells you how much the actual fair probability and odds of an event are.
In order to calculate the margin, the given odds should first be converted into implied probabilities. Once the event probabilities are known, then we can sum them to get the total - which, in a fair market, would be 100%. Bookmaker's odds, however, usually sum up to 105%, the 5% is their "juice". The margins can vary from bookmaker to bookmaker, however. With the lowest margings being around 2% and the highest margins reaching 10% or above.
For instance, imagine the moneyline between Manchester City and Liverpool is listed in a bookmaker as 1.9 x 1.9. This means that both teams have equal chances of winning, according to this bookmaker. Theoretically, if two outcomes have the same probability of occurring, then both teams have a 50% chance - which adds up to 100%. If we convert the given odds into a probabiliy however, we'll see that the implied probabilities are actually 52.63%. This means that the bookies are actually charging a 5.26% margin on this line.
The following formula can be used to calculate the margin of a 2-way market, for instance.
Margin = ( (1 / decimal odds A) + (1 / decimal odds B) - 1 ) x 100%