No-vig calculator
Enter the American odds for both sides of a market to see the true implied probability after the bookmaker's margin (vig) is removed.
What this does
When a sportsbook lists Lakers -110 and Celtics -110, the raw implied probabilities don't sum to 100% — they sum to about 104.8%. The extra 4.8% is the book's margin (the “vig”). De-vigging strips that margin to produce probabilities that sum to exactly 100%, giving you a fair-price reference.
This is the standard tool for comparing prices across sportsbooks, against Kalshi's exchange odds, or against your own model. Without de-vigging, you'd systematically underestimate the value of every side because the book's margin is baked into both prices.
The math
For two outcomes A and B with raw implied probabilities pA and pB:
p_A_novig = p_A / (p_A + p_B)
p_B_novig = p_B / (p_A + p_B)
This is called multiplicative normalization. For markets with more than two outcomes (e.g. futures), same logic applies — divide each raw implied by the sum of all of them.
When does vig matter most?
Vig is highest on outright futures (15-25%), props (8-12%), and parlays (compounds per leg). On a typical NFL or NBA game line, vig is 4-5%. The higher the vig, the more important it is to de-vig before comparing.
For a deeper dive, see the vig glossary entry and no-vig glossary entry.
No-vig calculator — FAQ
What is the vig (vigorish)?+
The vig is the bookmaker's margin baked into the odds. When DraftKings lists Lakers -110 / Celtics -110, the implied probabilities are 52.4% + 52.4% = 104.8%. The 4.8% above 100% is the vig — the book's profit margin if action balances on both sides.
How is no-vig probability calculated?+
For a two-outcome market: divide each side's raw implied probability by the sum of all sides' raw implied probabilities. Lakers raw = 52.4% / 104.8% = 50.0%. The result sums to exactly 100%, with the vig stripped out.
Why does no-vig matter when comparing to Kalshi?+
Kalshi prices are pure exchange prices — no built-in vig (just a small per-contract trading fee). Comparing Kalshi's implied probability directly to a sportsbook's raw implied probability would penalize Kalshi for not having the book's hidden margin. No-vig levels the playing field so you can spot real edges.
What if my market has more than two outcomes?+
The same multiplicative normalization works for any number of outcomes. For a 6-way market (e.g., NFL MVP with 6 contestants), sum all raw implied probabilities and divide each by the total. For outright futures with very wide fields, this method is still standard but vig can run 15-25%.
Are there other de-vigging methods?+
Yes — the multiplicative method is the standard, but Pinnacle's 'power' method and additive normalization both exist. Pinnacle's method is more accurate at the extremes (very heavy favorites/longshots) but the multiplicative method is the industry default and what sportsbook APIs return when they expose de-vigged numbers.