What Is Vig (Juice) in Sports Betting?
Sportsbooks do not gamble. Every line on the board has a fee stitched into it so the book profits whichever side wins, and that fee, the vig, is the single biggest reason most bettors lose. You cannot avoid it entirely, but once you can see it, you can stop paying more of it than you have to.
What is vig?
Vig, short for vigorish and also called juice, is the sportsbook's commission, baked directly into the odds. The standard -110 on both sides of a spread is the classic example: risk 110 to win 100 on either side. Two equal bettors on opposite sides hand the book 220 and the book pays out 210. The leftover 10 is the vig.
You never see it as a line item. It hides inside prices that are slightly worse than fair on both sides.
How do you calculate the vig?
Convert both sides to implied probability and add them. Fair odds sum to exactly 100 percent. Anything above is vig. Standard -110/-110 implies 52.38 percent on each side, summing to 104.76: about 4.5 percent of all money wagered. A -120/+100 market sums to 104.5. A prop at -130/-110 sums to 104.1.
The quick conversions: minus odds are the number over the number plus 100; plus odds are 100 over the number plus 100.
How much does vig actually cost you?
At standard -110, you must win 52.38 percent of your bets just to break even. A bettor who genuinely picks 52 percent winners, which takes real skill, still loses money at -110. That is the entire business model: the vig sets the bar above a coin flip and most of the public never clears it.
Compounding makes it worse. Parlays multiply the vig with every leg, which is why a five-leg parlay can carry an effective margin north of 20 percent while a straight bet carries 4.5.
How do you pay less vig?
Three habits. Shop lines: the same prop at -110 at one book and -118 at another is a permanent, riskless saving, and over a season the cheaper price is worth more than most handicapping insights. Prefer low-vig markets: main lines are priced tighter than obscure props and exotics. Avoid heavy parlay stacking unless the payout genuinely compensates for the compounded margin. None of this requires picking better; it is pure cost control.
Here's the bottom line
The vig is the house edge you pay for access, it is measurable on every market, and the difference between winning and losing bettors is often nothing more than who manages it. Know your break-even rate, shop your prices, and only bet where the evidence clears the bar. DataStreak shows the live odds from multiple books next to every prop's real hit rate, so both halves of that equation, the cost and the evidence, are on one screen.
Compare prop prices and hit rates side by side in the DataStreak Streak Finder.
