What does Margin mean in betting?

Margin in betting is the built-in edge the bookmaker holds in the line. It is closely related to bookmaker margin and shows how much of the market is priced in the operator’s favour.

How does it work?

If you convert the odds into implied probabilities and add them together, the total often comes out above 100%. That extra percentage is the margin. The higher it is, the worse the price for the player. So margin matters not as an abstract figure, but as a way to judge how expensive a market really is and how much the bookmaker is taking through the odds.