Definition
Fair value is the no-vig true price of a bet, used as a baseline for comparison. It removes the sportsbook’s margin from the listed odds.
For a two-sided market:
no-vig probability = side implied probability / total implied probability
American odds implied probability:
-110 = 110 / (110 + 100) = 52.38%
Worked Example
A point spread is listed at:
- Team A
-110 - Team B
-110
Each side implies 52.38%. Together, they total 104.76%, which includes the book’s margin.
Team A no-vig probability:
52.38 / 104.76 = 50.00%
So the fair value price for Team A is 50%, or +100.
If your projection gives Team A a 53% chance to cover, its fair odds are:
-100 × 0.53 / (1 - 0.53) = -112.77
At a market price of -110, the bet is priced better than your fair value.
Expected value on a $110 risk to win $100:
(0.53 × 100) - (0.47 × 110) = $1.30
Why It Matters
Fair value helps a bettor separate the sportsbook’s price from the cleaner no-vig baseline. It is useful when comparing lines, checking projections, and deciding whether a posted number is worth betting.