Vig & Juice — The Book's Margin
How the hold works, and why de-vigging reveals the true line.
The vig (or juice) is the commission baked into every price — how the book makes money regardless of who wins.
Where it hides
A fair coin flip should pay +100 each side. Books post -110 / -110 instead. Convert those to implied probability (each ≈ 52.4%) and they sum to 104.8% — that extra 4.8% is the hold (overround). On a balanced book, the book keeps it no matter the result.
De-vigging
Strip the overround proportionally and you get the no-vig (fair) line — the book's honest estimate of true probability. That's the baseline our Fair Value tool computes before comparing to the market, and it's how you tell a genuinely good number from one that just looks good.
Why it matters
Lower juice = more of your money working for you. Reduced-juice books (-105 instead of -110) and line shopping for the best price directly cut the hold you pay. Over a season, beating the vig is as important as picking winners.