No-vig calculator: remove the vig from betting odds

How do I remove the vig from odds?

1. Choose two-way or three-way and your odds format.
2. Enter the price of every outcome, taken from one book’s listing of that one market.
3. Read the vig and the fair probability and fair odds under each method.
4. To test a price, enter it and the stake: the table shows the expected value under each method.

The set must be complete and mutually exclusive: a moneyline, an over and an under on the same line, or all three results of a soccer game.

What is the vig?

The vig, or hold, is how far a book’s implied probabilities add up beyond 100%: vig = (sum of implied probabilities) − 1. At −110 on both sides each implied probability is 52.38%, they add up to 104.76%, and the vig is 4.76%. That is also why you must win 52.38% of the time at −110 to break even.

implied probability q = 1 / decimal odds
vig = q1 + q2 (+ q3) - 1
fair probability: the q values scaled so they add up to 1

Which de-vig method is most accurate?

No method is proven best, which is why the calculator shows all four. They agree closely on an even market and drift apart on a lopsided one. For −150 and +130 the vig is 3.48% and the favorite’s fair probability is 57.98% by the multiplicative method, 58.26% by the additive and Shin methods and 58.40% by the power method. The power method moves more of the margin onto the longshot, and SlateProof’s engine uses it by default.

Multiplicative: scale every probability by the same factor. Additive: subtract an equal share of the vig from each. Power: raise each probability to one exponent so they sum to 1. Shin: a model of insider trading by Shin (1993).

How do I de-vig a three-way market?

Choose three-way and enter the home win, the draw and the away win; the same methods apply to three outcomes. For example prices of +150, +250 and +190 the implied probabilities add up to 103.05%, a vig of 3.05%, and the power-method fair probabilities are 38.97%, 27.57%, 33.46%. The draw is an outcome like any other: leave it out and the result is wrong.

Can I de-vig a one-sided or milestone market?

No. A line such as “player to score 25 or more” lists only one side, so there is no complete set whose margin can be removed. SlateProof de-vigs only complete outcome sets and never a one-sided milestone. A rung that no reference prices directly can only be estimated from the same player’s other rungs with a fitted distribution, and that estimate is labeled as extrapolated with wider uncertainty.

How do I use fair odds to find +EV bets?

Expected value per $1 is the fair probability times the decimal price, minus 1: EV = p × d − 1. In the example, +145 is decimal 2.45, the power-method fair chance of the underdog is 41.60%, and EV = 0.4160 × 2.45 − 1 = 1.92%, or $1.92 on $100. Fair odds must come from a different, sharp market than the one you are betting into: a book’s own price never sets its own fair value. Expected value is a model claim, and the expected value guide covers uncertainty and sample size.

Do exchange prices need de-vigging?

Not in the same way. An exchange sells each side as its own contract, so there is no sportsbook margin to scale away, although the two sides can add up to a little over 100% because of the spread, and a taker fee applies. Use the odds converter to see a contract price after its fee.

Related calculators and guides

• Odds converter

  American, decimal, fractional, probability and contract prices.

• Profit boost calculator

  Use a fair chance to value a boost.

• Expected value guide

  Where fair probability comes from and how much data you need.

• Methodology

  How SlateProof builds fair value from reference prices.