DomVsBeta

Glossary · Math

No-Vig Odds (Fair Odds)

The odds with the bookmaker's margin removed — what a fair coin would pay.

Bookmakers build a margin (the vig or juice) into every market. To compare your probability to the market's, you first have to strip out that margin. The result is the no-vig price: what the market thinks the true probability is, before the bookmaker's cut.

Formula
For a two-way market with decimal odds d1 and d2:
  ip1 = 1/d1,  ip2 = 1/d2
  total = ip1 + ip2
  no-vig probability of side 1 = ip1 / total
  no-vig odds of side 1 = 1 / (ip1 / total)
Worked example
Market: 1.95 / 1.95.
  ip = 1/1.95 + 1/1.95 = 1.0256  (2.56% vig)
  no-vig prob = 0.5128 / 1.0256 = 0.50
  no-vig odds = 2.00 each side.
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