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Bookmaker margin (overround) calculator
A bookmaker never offers fair odds. The margin (overround) is built into the prices. This calculator shows how big it is and what the odds would be without it.
How it works
Add the implied probabilities of every outcome (1 / odds). The amount above 100% is the margin. Three-way odds of 2.10, 3.40, 3.60 sum to 104.8%, a margin of 4.8%.
To remove it we scale each probability down proportionally so they add to exactly 100%. That gives the fair probabilities and the fair odds.
Sharp books (Pinnacle, Betfair exchange) run small margins, so their fair prices are the best reference for a match.
18+ only. General information, not betting or financial advice. All guides