Compare n' Bet™
Compare n' Bet™
Strip the sportsbook's margin out of a two-way or three-way market to see the true implied probability on each side. The math behind evaluating whether a line has positive expected value.
When a sportsbook prices a two-way market, they don't offer you a 50/50 split on a coin flip. If they did, they'd make no money. Instead, they shade the prices on both sides so that the implied probabilities add up to more than 100%. That extra percentage is the sportsbook's margin, also called the vig, juice, or hold.
A standard -110 / -110 market looks fair, but it isn't. Each side implies a 52.38% chance of winning. Add them up and you get 104.76%, which means there's a 4.76% vig baked into the market. The sportsbook is earning that 4.76% regardless of which side wins, on average, across millions of bets.
The no-vig price (also called the fair price or zero-vig price) is what both sides would be priced at if the sportsbook took no margin. It's calculated by normalizing the two implied probabilities so they sum to exactly 100%. The result is an estimate of what the sportsbook actually believes the true probabilities are.
This matters because to know whether a bet has positive expected value, you need an honest estimate of the true probability. The offered implied probability is always inflated by the vig. The fair probability is your clean baseline for comparison.
A sportsbook offers +100 on Team A and -120 on Team B. Offered implied probabilities: 50.00% and 54.55%. Sum: 104.55%. Vig: 4.55%. Fair probabilities: 47.85% for Team A, 52.15% for Team B. Fair no-vig prices: +109 and -109. If you believe Team A has a better than 47.85% true chance of winning, +100 is a positive-EV bet. If you believe Team A has a worse than 47.85% chance, it's a negative-EV bet, even though the offered +100 looks "even money."
This calculator uses the standard normalization method, which assumes the vig is distributed proportionally across both sides. In reality, sharp books often apply more margin to the underdog than the favorite (this is called "shaded juice"). For high-precision work, professional bettors use more sophisticated vig-removal methods like the power method, log method, or Shin method, which give slightly different fair-probability estimates.
For most practical purposes, and for the two-way markets typical of US sports betting, the standard method is accurate enough to spot value and understand the real cost of the vig.
Three-way markets (common in soccer, where you bet on home/draw/away) work the same way. Add all three implied probabilities, they'll sum to more than 100%, and you normalize each one by the total. Switch the market type dropdown above to see how this works in practice.
The expected value guide explains how to turn fair probabilities into an edge. The line shopping guide shows why different books charge different vig and why shopping the best price matters. The odds converter handles individual format conversions.
This calculator is for informational purposes only. Compare n' Bet does not provide betting advice, guarantees, or predictions. If you or someone you know has a gambling problem, call 1-800-522-4700 or visit ncpgambling.org.