No-Vig Fair Odds Calculator

No-vig odds and fair probability

Sportsbook odds include a margin that makes the implied probabilities across outcomes add to more than 100%. A no-vig calculator removes that excess and rescales the outcome probabilities to total 100%. The resulting fair odds are a market-based estimate, not a guarantee or a prediction.

For a two-way market priced -110 on both sides, each raw probability is about 52.38%. Proportional normalization produces a 50% no-vig probability on each side, equivalent to fair odds of +100.

How the no-vig calculation works

First convert both prices to implied probabilities. Then divide each probability by the sum across outcomes. Convert the normalized probability back to American odds to get the fair price. This calculator uses proportional normalization, one common method for a two-outcome market.

For three-way markets, different methods for allocating the margin can produce different fair probabilities. Use a method suited to the market and disclose it when comparing model outputs.

Compare your number with fair odds

If your estimated win probability is higher than the no-vig probability, that may suggest a price difference worth researching. Check that your model and the market refer to the same outcome, time period, and settlement rules. A market consensus is a reference point, not ground truth.