Every price a sportsbook posts has its cut baked in. Add up the implied probability of both sides of a game and you get more than 100%, which is impossible in the real world and exactly how the book gets paid. If you want to know what a bet is actually worth, you first need no vig odds: the price with that cut removed.
This guide explains what no-vig odds are, how to devig odds by hand with three different methods, why the methods disagree on lopsided markets, and how to use fair odds to spot bets worth making.
The short version: to devig odds, convert each side's price to an implied probability, add them up, and remove the extra above 100% so the probabilities total exactly 100%. The result is the fair, no-vig price. The multiplicative method is the standard for balanced markets, while the additive and power methods handle heavy favorites differently. Compare a sportsbook's price to the fair price and you know whether a bet has positive expected value.
What Are No Vig Odds?
No vig odds, also called fair odds or true odds, are what a market's prices would look like if the sportsbook took no margin. They are the market's estimate of each outcome's real probability, written as odds.
The vig (short for vigorish, also called juice or the hold) is the margin a book builds into its prices. On a standard spread priced at -110 on both sides, you risk $110 to win $100 no matter which side you pick. If the game is a true coin flip, the fair price is +100 on both sides, and the gap between +100 and -110 is the book's cut.
Devigging is the process of working backward from the posted odds to that fair price. It matters because almost every useful betting calculation, from expected value to bet sizing, starts from the true probability, not the posted one.
Why Posted Odds Add Up to More Than 100%
Every American price converts to an implied probability:
- Negative odds: odds ÷ (odds + 100). So -110 is 110 ÷ 210 = 52.38%.
- Positive odds: 100 ÷ (odds + 100). So +130 is 100 ÷ 230 = 43.48%.
Do that for both sides of a -110 / -110 market and you get 52.38% + 52.38% = 104.76%. The extra 4.76% is called the overround. It doesn't mean either team is more likely to win. It means the book has inflated both prices so that, on balanced action, it keeps money regardless of the result.
The overround also tells you the book's hold. In this market the hold is 1 - (1 ÷ 1.0476) = 4.55%, the share of total money wagered the book expects to keep. A sharper market at -105 / -105 adds up to 102.44%, a hold of about 2.38%. Our guide to sharp and soft sportsbooks explains why some books run thinner margins than others, and why those books make the best starting point for devigging.
How to Devig Odds in Three Steps
Whatever method you use, the workflow is the same.
Here is the math for the last two steps, using the multiplicative method:
- Team A: 60.00% ÷ 103.48% = 57.98%. As American odds, that is -(57.98 ÷ 42.02) × 100 = -138.
- Team B: 43.48% ÷ 103.48% = 42.02%. As American odds, that is (57.98 ÷ 42.02) × 100 = +138.
So the book is asking you to lay -150 on a team whose fair price is -138, or take +130 on a team whose fair price is +138. Both sides are priced worse than fair, which is what the vig does.
The Three Main Devig Methods
The step that changes between methods is how you remove the overround. Each one makes a different assumption about where the book put its margin.
Multiplicative (proportional). Divide each implied probability by the total. It's the simplest method, the one most people mean when they say "devig", and on balanced markets it works well. Its assumption is that the book shaded every side by the same percentage.
Additive. Split the overround evenly and subtract the same number of percentage points from every side. In the example, the overround is 3.48 points, so each side loses 1.74 points. Because a fixed amount is a bigger share of a small probability, this method takes relatively more off the underdog.
Power. Raise every implied probability to the same power k, choosing k so the results add up to exactly 100%. There's no closed-form answer, so you solve for k by trial and error or let a calculator do it. In the example, k is about 1.053. The power method takes the most off longshots, which matches how many markets are actually priced.
You may also see the Shin method, which models the book's margin as protection against bettors with inside information. It lands close to the power method in most markets and is mainly used for multi-outcome races and futures. You don't need it to devig everyday spreads and moneylines.
Why the Methods Disagree on Big Favorites
On a balanced market, every method gives the same answer. At -110 / -110, each side is 52.38%, and every method returns 50% and +100. The methods only split apart when one side is a heavy favorite.
That split comes from the favorite-longshot bias, a well-documented pattern where longshots tend to be overpriced relative to their true chances. Books know bettors overpay for longshots, so they often put more of their margin on that side. Methods that take more vig off the longshot try to account for it.
Take a heavy favorite at -400 against an underdog at +300. Implied probabilities are 80.00% and 25.00%, for a total of 105.00%. Here is the underdog's fair price under each method:
The math behind each bar:
- Multiplicative: 25.00% ÷ 105.00% = 23.81%, or +320.
- Additive: 25.00% - 2.50% = 22.50%, or +344.
- Power: with k = 1.10, 0.80^1.10 + 0.25^1.10 = 78.24% + 21.76% = 100%. The underdog's 21.76% is +359.
That is a 39-point gap in fair price on the same game. It matters, because the method you choose can decide whether a bet looks profitable at all.
Using No-Vig Odds to Find +EV Bets
Fair odds are the benchmark for positive EV betting. If a book offers a better price than the fair price, the bet has positive expected value. If it offers a worse one, it doesn't.
Back to the first market. The no-vig price on Team B is +138, a 42.02% chance. Say another sportsbook offers Team B at +150:
- A $100 bet at +150 wins $150.
- Expected value = 0.42017 × $150 - 0.57983 × $100 = $63.025 - $57.983 = +$5.04 per $100, or about +5.0%.
Now the -400 / +300 game. Suppose a soft book offers the underdog at +340. Compare it to each fair price:
- Multiplicative (23.81%): 0.2381 × $340 - 0.7619 × $100 = $80.95 - $76.19 = +$4.76. Looks like a bet.
- Additive (22.50%): 0.2250 × $340 - 0.7750 × $100 = $76.50 - $77.50 = -$1.00. Slightly negative.
- Power (21.76%): 0.21765 × $340 - 0.78235 × $100 = $74.00 - $78.24 = -$4.24. Clearly negative.
Same bet, same market, three different verdicts. This is why careful bettors check a price under several methods before betting a longshot, and pass when the methods disagree on the sign of the edge. Our explainer on what EV means in betting covers the expected value formula in more depth.
Which Devig Method Should You Use?
There's no single right answer, but a few rules of thumb hold up well:
- Balanced markets (both sides between about -130 and +130): the methods barely differ. Multiplicative is fine.
- Heavy favorites and longshots: use power, or check multiplicative and power side by side and use the more conservative result.
- Three-way and multi-outcome markets (soccer moneylines, futures): power or Shin usually fits better than multiplicative, though on tight three-way markets the gap is small.
- When in doubt, be conservative. Treat a bet as +EV only if it's +EV under the strictest method you trust.
For a three-way example, take a soccer match at home +150, draw +240, away +190. Implied probabilities are 40.00%, 29.41% and 34.48%, a total of 103.89%. Multiplicative gives fair odds of about +160 / +253 / +201, and power gives about +158 / +255 / +201. Close, but not identical.
The method matters less than the source. A perfect devig of a soft book's inflated prop is still a soft number. Start from the sharpest market you can find, and when you can, average the devigged probabilities from several sharp sources instead of trusting one.
Common Devigging Mistakes
- Devigging a soft book's price and calling it the truth. The output is only as good as the input. Anchor to sharp books, exchanges or prediction markets with low margins.
- Mixing prices from different books in one devig. Taking the best price on each side from two books gives you a low overround, but it's no longer one market's view. Devig each source on its own, then combine.
- Forgetting the draw. In three-way markets, leaving out the draw makes the total look far below 100% and produces nonsense.
- Rounding too early. Carry two decimals on probabilities until the final step. Rounding 43.48% to 43% shifts the fair price by several points.
- Ignoring the method on longshots. As the -400 / +300 example shows, a multiplicative devig can make a longshot look profitable when the power method says it isn't.
- Using stale prices. Fair odds move with the market. A devig from an hour ago may not match the price you're about to bet.
Devig Odds Faster With a Calculator
Doing this by hand is worth learning once, but it's slow, and the power method needs trial and error to solve. Our free no vig calculator takes both sides of a two-way market in American odds and returns the fair odds, fair probability and the vig removed, with multiplicative, additive and power methods built in.
At scale, the job gets bigger. Finding +EV bets means devigging sharp prices for thousands of markets and comparing them against every book, many times a minute. AVO's positive EV betting tool does that in real time across 70+ sportsbooks, exchanges and prediction markets, and shows the edge under several devig methods so you can see when they agree.
Frequently Asked Questions
What does devig mean in betting? Devig means removing the sportsbook's margin from a set of odds so the implied probabilities add up to 100%. The result is the fair, or no-vig, price.
How do you calculate no vig odds? Convert each side to implied probability, add them up, and divide each side by the total (the multiplicative method). Convert the results back to odds. For -150 / +130, that gives fair odds of -138 / +138.
What is the best devig method? Multiplicative works well on balanced markets. On heavy favorites and longshots, the power method is often more realistic because it takes more of the margin off the longshot. Checking both is a safe habit.
What is the difference between vig and hold? The overround is how far the implied probabilities exceed 100%. The hold is the share of money wagered the book expects to keep, calculated as 1 - (1 ÷ total). At -110 / -110, the overround is 4.76% and the hold is 4.55%.
Are no vig odds the true odds? They are the market's best estimate of the true odds, and only as reliable as the market they come from. Fair odds from a sharp, liquid market are much more trustworthy than fair odds from a soft prop.
Can I devig a three-way market? Yes. Include every outcome, including the draw, and remove the overround across all three. The same methods apply.
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