No-Vig Calculator

Overround, margin and vig

Add the implied probabilities of every outcome in a market and you get more than 100%. That total is the overround: 1.91 on both sides of a total gives 52.36% + 52.36% = 104.7%. The margin is what the book keeps of every stake on average, 1 - 1 / overround, here 4.5%. Both words describe the same edge from two angles.

How the fair odds are computed

This calculator uses the multiplicative method: each implied probability is divided by the overround so the results sum to exactly 100%, and the fair odds are the inverse of those true probabilities. It is the standard first estimate. More refined methods (power, Shin) shift a little more of the margin onto longshots, which matters on heavy underdogs and less on prices near even.

Why it matters

A price is only good if it beats the true probability, not the implied one. De-vigging a sharp closing line, ideally from Pinnacle where margins are among the lowest in the market, gives the best available estimate of that true probability, the reference used by every serious bettor and by the closing line value calculator.

In the Strategy Builder

The vig filter targets markets by their margin and the implied probability filter works on de-vigged probabilities, so a 60% threshold means the same thing in every league. Backtests settle at the real closing price, margin included, the way your bets would.