De-vig calculator
Enter the posted odds for each outcome of a market. The calculator converts them to implied probabilities, measures the bookmaker’s margin (the overround), and divides it back out to show the fair, no-vig odds.
| Outcome | Posted odds | |
|---|---|---|
Overround
104.1%
Bookmaker vig
4.1%
| Outcome | Implied | Fair (no-vig) | Fair decimal | Fair American |
|---|---|---|---|---|
| Yes | 56.5% | 54.3% | 1.84 | -119 |
| No | 47.6% | 45.7% | 2.19 | +119 |
De-vig by the normalization method: each posted price is converted to an implied probability, summed to the overround, then divided back out so the fair probabilities total 100%. Useful for reading the market’s true odds on a prediction-market or sportsbook line. This is a math tool, not advice, it places no bets.