Enter both sides of a two-way market. The calculator returns the sportsbook's hold percentage — the share of every dollar wagered the book keeps, on average, when action is balanced — plus per-side de-vigged probabilities.
The hold (sometimes called "vig" or "juice" in conversation) is the sportsbook's built-in margin on a market. If a book's two sides imply 50% / 50% true probability, they price them at -110 / -110. Each side's implied probability is 52.38%, summing to 104.76% — that 4.76% above 100% is the hold.
The hold percentage isn't quite the share the book actually keeps. Mathematically, hold = 1 − (1 / sum of implied probabilities). On a 104.76% market, the actual hold is roughly 4.55% — the share of every dollar wagered the book retains if action is split exactly evenly between the two sides.
Low-hold markets are sharper — the book is confident in its line and is willing to take action with thin margin. High-hold markets (player props, same-game parlays, derivatives) are looser, less efficient, and carry compounded juice that eats even meaningful edges.
Sharp bettors prefer low-hold markets because the de-vigged fair price is closer to the offered price — meaning less of every bet is wasted on the book's tax. Hold below 3% is sharp; 4–5% is typical retail; 6%+ is high. Player-prop markets routinely hold 8–15%, which is why beating them sustainably is so hard.
To strip the hold out and see the market's de-vigged "fair" prices, use the No-Vig Calculator.