Free tool
Enter two prices and see the sportsbook margin, raw implied probabilities, and no-vig fair probabilities.
Hold is the amount by which the two posted implied probabilities add up to more than 100%. That excess is the built-in margin.
No. They are the market's own probabilities after removing margin. They are a baseline, not a forecast.
Higher hold makes a market more expensive. The calculator shows the price of the market, not which side to take.
Fair probabilities are the posted market after removing margin. They are not a forecast or a recommendation. 21+ · Bet responsibly
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The honest explainer
Hold is the book's posted margin on a market: how far the two implied probabilities overshoot 100%. It's the price of playing, measured — and it varies more than most bettors realize, across books, sports, and market types.
Its honest use is comparison shopping. The same game at 2% hold and 5% hold is the same product at very different prices.
Standard −110 / −110: each side implies 52.4%, summing to 104.8% — about a 4.8% overround. A book offering −105 / −105 sums to 102.4% — half the price for the identical market. Over hundreds of bets, that difference alone separates 'slowly losing' from 'quickly losing.'