Fair odds are the price of a bet with no house cut — the price you'd get in a market that only had to break even. Every number on the Props Edge card is a fair price. A real sportsbook adds a margin (the vig or juice), so it always pays a little less than fair.
How the vig hides in a line
Take a two-way market priced -110 / -110. Convert each side to implied probability:
Other side, also -110 → 52.4%
Total: 104.8% — that extra 4.8% is the vig.
A fair market would sum to exactly 100%. The book's book adds up to more.
Stripping the vig (de-vigging)
Divide each side's implied probability by the total so they sum to 100%:
That no-vig number is the book's actual opinion. On a lopsided line (-160 / +140) the same method gives roughly 60% / 40% after de-vigging — the sharp book's honest estimate, which is usually the best single estimate available.
Why it's the whole game
You only have an edge when your own probability estimate is higher than the price implies. If a book offers +120 (45.5% implied) and you honestly think the bet wins 50% of the time, that gap is your edge. If you think it wins 44%, you have no bet — even if you "like" it.
Props Edge prices every pick as fair odds, then shows the gap to a real sharp book's de-vigged number as Mkt Edge. The EV calculator turns a price and a fair win % into an expected value in dollars.