No-Vig / Fair Odds Calculator
Strip the bookmaker margin (vig) from sharp 2-way and 3-way market odds to find the true implied probability and zero-vig fair odds.
How no-vig fair odds & margin calculations work
Bookmakers and betting exchanges do not offer pure probability odds. They build a mathematical margin into their pricing known as the overround, vig (vigorish), or juice. This margin ensures that regardless of the sporting outcome, the bookmaker retains a mathematical edge over the betting public.
Sharp bookmakers (such as Pinnacle) and betting exchanges operate with extremely tight margins (often 1.5% to 3.5%) and high betting limits. Because sharp markets are driven by high volumes of professional syndicates and sharp bettors, their margin-adjusted prices represent the single most accurate reflection of an event's true statistical probability available anywhere.
Removing the vig (proportional method): To calculate true zero-vig odds, we first compute each outcome's raw implied probability (1 / decimal odds) and sum them to determine the bookmaker's overround. We then divide each outcome's implied probability by the total overround, yielding the true fair probability. Inverting that probability (1 / fair probability) reveals the genuine fair odds with all bookmaker margin stripped away.
Worked example: 3-way football match
Consider a Premier League fixture priced by a sharp bookmaker as follows:
- Home win: 2.10 (raw implied probability: 47.62%)
- Draw: 3.40 (raw implied probability: 29.41%)
- Away win: 3.80 (raw implied probability: 26.32%)
Total market overround is 103.35% (a bookmaker margin of 3.24%). Stripping this 3.24% margin gives the true fair probabilities and decimal odds:
- Home win: 46.07% true probability → 2.17 fair odds
- Draw: 28.46% true probability → 3.51 fair odds
- Away win: 25.47% true probability → 3.93 fair odds
If a recreational UK bookmaker (such as Bet365 or SkyBet) offers odds higher than 2.17 on the Home team (for instance, 2.25 on a price boost or promotional special), you have confirmed a mathematically profitable positive expected value (+EV) bet.
Using fair odds for +EV and Kelly staking
Finding value in sports betting relies entirely on comparing soft bookmaker odds against sharp, zero-vig fair odds:
- Expected Value (+EV): Whenever a bookmaker pays out at a price higher than the no-vig fair odds, the bet has positive long-term value. Click Send to +EV → to instantly compute your exact mathematical edge and expected profit per bet.
- Kelly Criterion: Optimal bankroll growth requires wagering an amount proportional to your calculated edge and probability. Click Send to Kelly → to determine the ideal fractional Kelly stake size without risking unnecessary drawdown.