No-vig (fair odds) calculator
Strip the margin out of any quote to see what the book actually thinks the probabilities are, using the two standard methods side by side.
| Side | Quoted | Implied | No-vig (multiplicative) | No-vig (power) | Fair odds |
|---|---|---|---|---|---|
| A | -150 | 60.0% | 58.0% | 58.4% | -138 · 1.725 |
| B | +130 | 43.5% | 42.0% | 41.6% | +138 · 2.380 |
Overround 3.48%. The multiplicative method scales every side by the same factor; the power method shrinks longshots more, which better matches how books shade favorites and underdogs. Neither is the book's private estimate — both are the best you can infer from the quote.
The two methods
Multiplicative: fair p = p / Σp. A −150 / +130 market (60.0% + 43.5% = 103.5%) becomes 58.0% / 42.0%.
Power: find k such that Σ p^k = 1, then fair p = p^k. The favorite loses a little less margin than the underdog, which is how books actually shade prices. On the same market the power method gives roughly 58.5% / 41.5%.
Using it
Devig a sharp, low-margin book to estimate a fair line, then compare softer books against it. Where a soft book's price implies a lower probability than the fair estimate, it is offering value; where two books' best prices sum under 100%, it is offering an arbitrage. Our sportsbook rankings show which books run the lowest margins.
Frequently asked questions
What are no-vig odds?
The prices a book would quote if it took no margin: the implied probabilities scaled so they sum to exactly 100%. They are the closest thing to the book's own estimate of the outcome that you can read from a quote.
Multiplicative vs power devig — which is right?
Multiplicative divides every side by the sum; simple, and fine near even money. The power method raises each probability to a common exponent so that they sum to 1, which removes more margin from longshots — matching the favorite–longshot bias books actually price in. Serious bettors use power or Shin methods for large favorites.
Why would an arbitrageur care about no-vig odds?
They don't need them — an arb is about the prices you can get, not fair value. But no-vig odds explain why books disagree: each has its own estimate and its own margin. The books whose no-vig lines lag the market are where arbs appear.
Related: What no-vig odds are · Vig calculator · Sportsbook margins, measured · Odds converter
Educational tool. Verify every price on the venue before acting; nothing here is financial or betting advice.