Hold Calculator
Enter both sides of a market to see how much the book keeps and the fair odds without the margin.
American odds. -110 / -110 is the standard spread market: the book holds about 4.5%.
Hold is the share of all money bet the book expects to keep if action is balanced. Overround is how far the implied probabilities add up past 100%.
Find the lowest-hold price
The same market can carry very different hold from one book to the next.
Every book side by side
The free line board shows every tracked sportsbook on the same game, so you can see which book is off the market number before you bet.
Exchanges and prediction markets
Novig, ProphetX, Kalshi and Polymarket often price with much less margin than a sportsbook. ThunderBet shows them next to the books.
Frequently asked questions
Hold is the share of the money bet on a market that the sportsbook expects to keep if the action is balanced. A -110 / -110 spread market has a hold of about 4.55%.
Convert each side to implied probability and add them up. Hold = 1 - 1 / (sum of implied probabilities). For -110 / -110 the sum is 104.76% and the hold is 4.55%.
Overround is how far the implied probabilities add up past 100% (4.76% at -110 / -110). Hold expresses the same margin as a share of money wagered (4.55%).
A market where the implied probabilities barely add up past 100%, for example -105 / -105 (about 2.4% hold). Lower hold means less of your money goes to the book over time.
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