Definition
Vig (vigorish) is the book's built-in commission taken on every bet. On a standard −110/−110 spread, both sides pay 10 cents above true 50/50 odds. If $100 is bet on each side ($200 total), book pays out $190.91 to the winner, keeping $9.09 — a 4.55% margin. Vig is baked into the price, not charged separately. Higher vig (−115/−115) requires a 53.5% win rate to break even. Vig is the primary structural barrier for recreational bettors.
Worked Example
Standard spread: −110 each side. To break even, win rate needed = 110 ÷ (110 + 100) = 52.38%. Reduced juice at −105/−105: breakeven = 105 ÷ (105 + 100) = 51.22%. Over 1,000 bets at $110 each, the difference is roughly $11,600 in additional breakeven threshold. Reduced-juice books save sharp bettors thousands per year.
Why It Matters
Vig is a constant tax. Shopping for the lowest juice is free edge — finding −105 instead of −110 on identical lines improves long-run ROI by 1.2 percentage points with zero additional handicapping required.