Remove the bookmaker's margin from any market and see the true, fair odds behind the price. Enter the odds on each side — we return the no-vig probability and fair line for every outcome, plus the book's hold.
| Outcome | Fair probability | Fair odds |
|---|---|---|
| 1 | 50.0% | 2.00 |
| 2 | 50.0% | 2.00 |
Every bookmaker price has a margin baked in — the vig (also called juice, overround, or hold). It's why a coin-flip market isn't priced at 2.00 / 2.00 but at something like 1.91 / 1.91: those two prices imply a total probability of more than 100%, and that excess is the book's built-in edge.
Devigging is the process of stripping that margin back out to recover the book's *true* opinion of each outcome — the no-vig fair odds and fair probability. The most common method (and the one we use ourselves on Pinnacle) is multiplicative / proportional: take each side's implied probability, then divide by their sum so they add back to exactly 100%.
Why it matters: the no-vig price is your reference for fair value. When a soft bookmaker offers a price whose implied probability is *lower* than the sharp no-vig probability, you're getting an edge — that gap, priced against the sharpest available market, is exactly what a value bet is. Comparing a soft price to the no-vig price is also how you measure closing line value (see our Closing line value calculator).
It removes the bookmaker's margin (the vig) from a market and returns the true, fair probability and fair odds for each outcome. Bookmaker prices imply a total probability above 100%; devigging renormalises them back to 100% so you can see the book's genuine opinion on each side.
The most common method is multiplicative: convert each price to its implied probability (1 ÷ decimal odds), add them up (this total is above 100% because of the vig), then divide each implied probability by that total. The results sum to 100% and are the no-vig fair probabilities; take the reciprocal for fair odds.
The no-vig price of a sharp market (like Pinnacle) is the best available estimate of the true probability. If a soft bookmaker offers odds whose implied probability is lower than that fair probability, the difference is your edge — a positive expected-value bet. Comparing your price to the no-vig closing line is also how closing line value is measured.
Multiplicative (proportional) splits the margin evenly across implied probabilities and is what we use ourselves. The power method assigns more of the margin to favourites, which some argue better reflects how books price lopsided markets. On balanced markets they agree; on heavy favourites they can differ by a point or two. Use multiplicative unless you have a specific reason not to.