Removing vig separates a quoted market into normalized probabilities that sum to 100%. It is a useful baseline for price analysis, not a guaranteed forecast.
Last reviewed: 2026-08-10
Measure the overround
Convert every outcome to implied probability and add them together. A total above 100% represents the quoted market overround.
Normalize each outcome
Divide each raw implied probability by the combined total. The adjusted probabilities then sum to 100%.
Understand the limitation
Proportional normalization does not model favorite-longshot bias or asymmetric margin. For thin or unusual markets, compare multiple books and methods.
Step-by-step workflow
- 1Enter every mutually exclusive outcome.
- 2Convert each price to implied probability.
- 3Add the probabilities to find overround.
- 4Divide each probability by the total.
Frequently asked questions
Is no-vig probability the true probability?
No. It is a market-derived estimate after one margin adjustment.
Can I remove vig from one price?
Not reliably. You need the prices for all mutually exclusive outcomes in the market.