How to calculate a sportsbook's hold
Add up the implied probabilities of both sides of a market and you get more than 100%. The excess is the hold — the book's margin for hosting the bet. Standard -110/-110 totals carry about 4.5%.
From hold to no-vig fair odds
Strip the hold out (normalize both probabilities to sum to 1) and you get the no-vig fair odds: the market's honest opinion. Comparing a book's posted price to the fair price across the whole market is exactly how The Edge board on this site finds +EV lines.
