Implied Probability Calculator
Convert odds to implied probability or remove the vig to find true probabilities for both sides of a market.
How Implied Probability Works
Every set of betting odds can be expressed as an implied probability. This probability tells you the break-even win rate: if an outcome wins more often than its implied probability, betting on it is profitable long-term.
The Vig (Overround)
Sportsbooks don't offer fair odds. They add a margin (vig or juice) so that the implied probabilities of all outcomes sum to more than 100%. A typical NFL spread market has both sides at -110, giving a combined implied probability of 104.76% and a vig of 4.76%.
Finding True Probabilities
The no-vig calculator normalizes the implied probabilities so they sum to exactly 100%. This gives you the market's true assessment of each outcome, removing the bookmaker's edge. Compare these true probabilities to your own models to identify value.
Frequently Asked Questions
What is implied probability in sports betting?
Implied probability is the estimated likelihood of an outcome as reflected by the odds. It is derived by converting odds into a percentage. For example, -200 American odds imply a 66.67% probability. Sportsbooks build their profit margin (vig) into the odds, so implied probabilities from market odds will always sum to more than 100%.
How do I remove the vig from odds?
To remove the vig, convert both sides to implied probabilities, add them together (this gives the overround), then divide each side's implied probability by the overround. For example, if Side A is 52.38% and Side B is 52.38% (total 104.76%), the no-vig probabilities are 52.38/104.76 = 50% each.
Why is no-vig probability important?
No-vig (or true) probability removes the sportsbook's margin, giving you the market's actual assessment of each outcome's likelihood. This is essential for finding value bets: if your estimated probability exceeds the no-vig probability, you may have found a positive expected value opportunity.
How do I calculate implied probability from American odds?
For negative odds: probability = |odds| / (|odds| + 100). Example: -150 = 150/250 = 60%. For positive odds: probability = 100 / (odds + 100). Example: +200 = 100/300 = 33.33%. These formulas give the implied probability including the vig.