Fundamentals
How Bookmaker Margins Work
The structural cost of betting into any market, before you've even picked a side.
What margin actually is
Bookmaker margin is the amount by which a market's implied probabilities sum to more than 100%. That extra percentage is the bookmaker's structural edge.
How to measure it
Add the implied probability of every outcome in a market. A zero-margin market sums to 100%; anything above is margin.
Why margin varies across markets
High-volume, mainstream markets tend to have tighter margins because competition keeps prices sharp.
FAQ
Can margin be zero or negative?
A true zero-margin market is rare; a negative one (arbitrage) can briefly appear across different books' prices.
Does a lower margin mean better value for every bet?
It means the market as a whole is priced closer to fair odds - not a guarantee for any specific selection.