No-Vig Calculator: Strip the Margin to Find the Fair Price
No-vig math rescales both sides of a two-way market so the implied probabilities sum to exactly 100%. What remains is the bookmaker's estimate of fair odds without the margin baked in. Use Pinnacle or Circa lines as your input and you have the sharpest publicly available reference for true price.
Why posted odds are not fair prices
Every sportsbook embeds margin on both sides of a market. At -110/-110, each side implies 52.38% win probability. Two outcomes cannot each have 52.38% probability in a binary market - they sum to 104.76%. The extra 4.76% is the hold.
To find fair probability, divide each implied probability by the total overround. At -110/-110: fair probability for each side = 52.38% / 104.76% = 50.0%. Fair odds: +100 each. That is what a competitive market without margin would price.
At asymmetric lines like -180/+155: Side 1 implied = 64.29%, Side 2 implied = 39.22%, total = 103.51%. Fair probabilities: 62.11% and 37.89%. Fair American odds approximately -164/+164.
Why Pinnacle and Circa are the right inputs
Not all no-vig outputs are equal. Stripping vig from a recreational book that is already badly positioned gives you a biased fair price. The input source matters as much as the calculation.
Pinnacle and Circa accept sharp money and adjust their lines accordingly. Their prices reflect two-sided action from sophisticated bettors. Their no-vig output is the closest thing to true market consensus available publicly. Most +EV shopping strategies start with Pinnacle no-vig as the benchmark and look for deviations at other books.
If you only have access to soft book prices, the no-vig output still improves on posted odds. Just treat the result with more uncertainty than you would a sharp market input.
Step by step: using this calculator
Use odds from the same book at the same timestamp. Mixing prices from two different books gives you a cross-market number, not the no-vig price of any individual market.
The output fair odds feed directly into the EV calculator. Get no-vig from a sharp book, then compare those fair odds against what your target book is offering. Positive EV means your target book is pricing the side above fair.
- Enter Side 1 Odds and Side 2 Odds from the same book and same market.
- Read Side 1 No-Vig % and Side 1 Fair Odds.
- Read Side 2 No-Vig % and Side 2 Fair Odds.
- Use the fair odds as your Win % input in the EV calculator to evaluate other books.
Worked example: -110/-110 and -180/+155
Standard game line at -110/-110: implied probabilities 52.38% each, total 104.76%. Fair probability each side: 50.0%. Fair odds: +100/+100. You are paying 4.76% hold on every market cycle.
Heavy favorite at -180/+155: Side 1 implied 64.29%, Side 2 implied 39.22%, total 103.51%. Fair probabilities: 62.11% and 37.89%. Fair odds approximately -164/+164.
If a competing book offers the underdog at +170 and fair is +164, the bet at +170 is +EV. That is the complete workflow: no-vig from a sharp source gives fair, then shop for anything priced above fair.
Fair side 1
-173
Fair side 2
+173
Vig removed
3.5%
Common mistakes when interpreting fair odds
Using no-vig output as a guarantee that one side is correctly priced. No-vig is a rescaling exercise. If the input book was poorly positioned, the fair output inherits that bias.
Comparing fair odds from different books as if they represent the same consensus. Sharp books and recreational books can differ meaningfully on the same game.
Treating no-vig output as a ceiling on what you should pay. Fair odds from a sharp market are a floor for value. If you can get better than fair, take it.
What most calculator pages skip
The OddsGuard extension shows lines from 75+ books side by side, which makes the no-vig workflow practical. Pull the Pinnacle or Circa price into the calculator, get fair odds, then scan which other books are offering the underdog above fair and take that position.