No-Vig (De-Vigged) Probability
Also known as: fair odds, de-vigged, novig
A sportsbook price with the vigorish removed, expressed as a clean probability that sums with the other side to exactly 100%. The standard reference for comparing prices across books.
No-vig probability is the sportsbook's implied probability after removing the bookmaker's margin. It's the cleanest reference point for comparing prices between books or against an exchange like Kalshi.
The standard method is multiplicative normalization: for a two-outcome market, divide each side's raw implied probability by the sum of all sides' raw probabilities. For multi-outcome markets like outright futures (where many players compete for one slot), divide each player's raw probability by the sum across the entire field.
Example: Lakers raw implied 52.4%, Celtics raw implied 52.4%. Sum = 104.8%. Lakers no-vig = 52.4 / 104.8 = 50.0%. Celtics no-vig = 50.0%.
For multi-outcome fields, the same logic applies but the target sum varies — outright winner markets target 100%, top-5 markets target 500% (since 5 winners exist), top-10 target 1000%, etc.
No-vig probabilities are what SportsBookISH uses to compute book medians + edges versus Kalshi. Comparing raw probabilities would systematically penalize Kalshi because the book numbers include 4-25% of vig that Kalshi doesn't charge (Kalshi's fee is a flat per-contract trade fee, not built into the price).
Three players priced at +500, +500, +500 (raw implied 16.7% each). Sum = 50%. After de-vigging to a target 100%: each is 33.3%. The 50% margin was the vig — these are realistically 33.3% each.
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By Kenny Hyder · SportsBookISH glossary
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