No-Vig (De-Vig) Calculator
Strip the bookmaker’s margin out of a two-sided market to reveal the fair probability and fair odds for each side. This is the number you compare every other price against.
Why de-vigging matters
Every two-sided price a book posts includes a margin (the "vig" or "juice"). Add up the implied probabilities of both sides and you get more than 100% — that surplus is the book's cut. The no-vig line removes it so the two sides sum back to exactly 100%, giving you the market's honest estimate of each side's probability.
The method is simple proportional de-vigging:
fair probability A = implied A ÷ (implied A + implied B)
Worked example
Side A -130 (56.5% implied), Side B +110 (47.6% implied). Together that's 104.1% — a 4.1-point margin. De-vigged: A = 56.5 / 104.1 = 54.3%, B = 45.7%. Side A's fair price is about -119.
This is what PropPrizm runs on
A no-vig line from one sharp book is good; a no-vig consensus across many books is better. PropPrizm de-vigs every book on every prop and blends them into one fair value, then flags where any single book is priced softer than that consensus. See the EV+ board.
Stop doing this by hand
These calculators do one bet at a time. PropPrizm's EV+ board runs the de-vig and EV math across every book, on every prop, live — and surfaces only the ones where a book is soft versus the market consensus.
See the EV+ board →Frequently asked questions
What does "no-vig" or "de-vig" mean?
It means removing the bookmaker’s built-in margin from a price so the two sides of a market add up to 100%. The result is the market’s fair estimate of each outcome’s true probability.
Which book should I de-vig for the truest line?
The sharpest, highest-limit market gives the best single no-vig line (many bettors use Pinnacle). A consensus of many books is more robust still, which is the approach PropPrizm uses.
How is the no-vig probability calculated?
Convert both sides to implied probability, add them to get the total (the overround), then divide each side’s implied probability by that total. That rescales them to sum to 100%.