- Choose an Odds Format and a Method: Closing Line Value, Relative Odds, Odds Ratio, Shin, or Balanced Odds.
- Enter Sharp Odds for each outcome. Optionally label them.
- Optionally enter Your Odds to compare against the sharp market.
- Read the output. De-vigged fair probabilities per outcome and the headline fair-value comparison.
Devig Calculator
A devig calculator that converts any sportsbook line to its fair odds by removing the vig. Compare devigged prices across books to find +EV bets.
How to Use This Calculator
What is a devig calculator?
A devig calculator removes the sportsbook's commission from a betting line to expose the underlying fair odds. The calculator supports five different devigging methods, each making slightly different assumptions about how to distribute the vig across outcomes: Closing Line Value, Relative Odds, Odds Ratio, Shin, and Balanced Odds.
Devigging and no-vig pricing refer to the same operation. Sharp bettors typically say devig and recreational sites typically say no-vig, but the math is identical for the most common method.
The five devigging methods
- Closing Line Value: assumes the sportsbook's closing line is the most accurate estimate of true probability. Standard for line-shopping analysis.
- Relative Odds (multiplicative, also called power method): the most common method. Divides each implied probability by the total to redistribute the vig proportionally.
- Odds Ratio: uses an odds-ratio transformation that gives slightly different answers on heavily skewed markets.
- Shin: assumes the vig comes from insider trading and adjusts probabilities asymmetrically. Common in academic literature.
- Balanced Odds: a simple additive method that subtracts equal amounts from each side to bring totals to 100%.
Worked example (Relative Odds method)
A two-way market is priced at -120 / +100.
\[
\begin{aligned}
\text{Side A} \ (-120) &= \dfrac{\strut 120}{\strut 220} = 54.55\% \\[6pt]
\text{Side B} \ (+100) &= \dfrac{\strut 100}{\strut 200} = 50.00\% \\[6pt]
\text{Sum} &= 104.55\% \\[6pt]
\text{Side A (devigged)} &= \dfrac{\strut 54.55\%}{\strut 104.55\%} = 52.18\% \\[6pt]
\text{Side B (devigged)} &= \dfrac{\strut 50.00\%}{\strut 104.55\%} = 47.82\%
\end{aligned}
\]
Those are the market's consensus fair probabilities with the vig removed.
Why devigging matters for sports bettors
Devigging is how +EV bettors identify mispriced bets. The devigged price from a sharp book represents the most accurate available estimate of true probability. Any time a soft book offers odds at a better price than the sharp's devigged fair line, the soft price is positive expected value by definition.
The DarkHorse Odds +EV Bet Finder automates this comparison across 50+ sportsbooks in real time. Use this calculator to verify individual opportunities or to understand the underlying math.
For the full strategy framework, read Intro to +EV Sports Betting. The closely related No Vig Calculator performs the same calculation under a different name.
Common mistakes
- Devigging a weak book. If the reference book's line is itself off-market, devigging it does not produce an accurate fair probability. Use sharp books like Circa Sports, Pinnacle, or a multi-book consensus as your reference.
- Forgetting about three-way markets. Soccer, hockey three-way moneylines, and several other markets need all outcomes in the calculation. Treating them as two-way distorts the math.
- Treating devigged probability as truth. The devigged line is the market's opinion. It is generally accurate but not infallible. Player props in particular often have meaningful inefficiencies.
- Comparing devigged probabilities to undevigged prices. Always compare apples to apples. The fair odds derived from the devig calculation should be compared to actual offered prices, not to other devigged probabilities.
Frequently Asked Questions
What is a devig calculator?
A devig calculator strips the sportsbook's commission out of a betting line to show the fair odds underneath. It supports five different devigging methods (Closing Line Value, Relative Odds, Odds Ratio, Shin, and Balanced Odds) for cases where the standard multiplicative approach may not best fit the market.
How do you devig odds?
Convert each side of the market to implied probability, sum the probabilities (the sum will exceed 100% because of the vig), then divide each side by the sum. The result is the devigged probability for each outcome. This is the Relative Odds method, also called multiplicative.
\[
\begin{aligned}
\text{Devigged Probability} &= \dfrac{\strut \text{Implied Probability}}{\strut \text{Sum of Implied Probabilities}}
\end{aligned}
\]
What is the difference between devigging and no-vig pricing?
There is no mathematical difference. Devigging and no-vig pricing are two names for the same calculation: removing the sportsbook's commission from a line to expose the underlying fair odds.
Which devigging method should I use?
Relative Odds (multiplicative) is the most common default and works well for balanced markets. Shin and Odds Ratio give different answers on heavily skewed markets. Closing Line Value is the right choice when comparing a current line to a closing line for line-shopping purposes. If unsure, start with Relative Odds.
Which sportsbook should I devig?
Sharp books like Pinnacle and Circa Sports are the standard reference. Their lines are tight and their devigged prices closely track true probability. Devigging a soft book's price reflects the soft book's pricing, which is rarely accurate.
Can I devig a parlay?
Not directly. Devigging a parlay requires devigging each leg first, then multiplying the legs together. Sportsbooks often add additional vig at the parlay layer, which complicates the math.
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