Calculator
Devig calculator — strip the vig, find the fair price
Enter both sides of any sportsbook market. Get the no-vig fair odds and the true implied probability — the foundation of every +EV betting workflow.
Why devigging matters
Every two-sided market at a sportsbook bakes in vig — the book's structural margin. The implied probabilities of the two sides always sum to more than 100%. That overround is the book's edge.
Devigging strips out the overround to estimate the 'true' probability of each side. It's the cleanest way to translate a market price into a probability you can compare against soft lines elsewhere.
The math
Multiplicative method: fair_prob(A) = implied(A) / (implied(A) + implied(B)).
Power method: find an exponent k such that implied(A)^k + implied(B)^k = 1. Slightly more accurate on lopsided two-way markets.
Shin method: accounts for informed-bettor share. Most accurate but requires market-specific parameters.
How pros use devigging
Anchor true probability to the sharpest book in a market (Pinnacle, Circa, Betfair Exchange). Devig those prices.
Compare to every other book in the market. Any line whose implied probability is below the sharp devigged fair value is a +EV bet — assuming your sharp anchor is more accurate than the soft book's line, which is the usual case.
Parlae automates this across 20+ US books for every market — devigged sharps anchored to Pinnacle/Circa, surfaced as +EV bets in real time.
Frequently asked questions
What does it mean to devig a line?
Devigging removes the sportsbook's margin from a two-sided market to estimate the 'true' probability of each side. It turns a -110/-110 quote (which sums to 104.76%) into a 50/50 fair probability.
How is devig calculated?
The simplest method (multiplicative): fair probability of side A = implied(A) / (implied(A) + implied(B)). For -110/-110: 52.38% / 104.76% = 50.00% each side.
Why is devigging important?
The devigged price is your best public-data estimate of true probability. Compare it to a softer book's price on the same outcome — if their implied probability is below the devigged fair value, the bet is +EV.
Which book should I devig?
Use the sharpest book you can find: Pinnacle, Circa, Bookmaker, or Betfair Exchange. These are markets that take large action from professionals and have the most efficient prices.
Is multiplicative devigging accurate?
It's an approximation. Power-method devigging (raising each implied probability to a power that normalizes them to 100%) is slightly more accurate on lopsided markets. Parlae uses both depending on market type.