Implied Probability Calculator

Implied probability is the percentage chance of an outcome happening as suggested by the betting odds. When a sportsbook offers -150 on a team, the implied probability is approximately 60%. This means the market believes that team has a 60% chance of winning. However, the true probability is slightly lower because the sportsbook builds in a margin known as the vig or juice. The vig is how the sportsbook guarantees profit regardless of the outcome. Understanding this margin is critical to finding value in betting markets.

To calculate the vig on a two-way market, add the implied probabilities of both sides. In a fair market, they would sum to exactly 100%. In practice, they sum to something higher like 104.8%. The excess, 4.8% in this case, is the vig. A standard -110/-110 line produces a total implied probability of about 104.76%, representing a vig of roughly 4.76%. Lower vig means better value for the bettor. Some sportsbooks offer reduced juice lines at -105 on both sides, cutting the vig roughly in half. Over thousands of bets, this difference compounds significantly.

Finding value means identifying situations where your estimated probability of an outcome exceeds the fair probability implied by the odds. First, remove the vig by dividing each side's implied probability by the total implied probability. This gives the no-vig or fair probability for each outcome. If you believe a team has a 55% chance of winning but the fair probability from the odds is only 50%, you have found a value bet with a 5% edge. The best bettors maintain their own probability models and systematically compare them against the market. Even small edges of 2-3% compound into substantial profits when applied consistently across hundreds of wagers with proper bankroll management.