Vig & Juice Explained: The Real Cost of Every Bet

1. What vig actually is

Vig — short for vigorish, also called juice or overround — is the commission a sportsbook builds into every line. It's how they make money regardless of which side wins. If the prices on a two-sided market reflected the true probabilities, the implied probabilities of both sides would sum to exactly 100%. Sportsbooks publish prices whose implied probabilities sum to more than 100%. That excess is the vig.

The book isn't betting against you in the way a casino is. They want balanced action — roughly equal money on each side — so that whichever side wins, the losers' stakes pay the winners' returns and the book pockets the difference between what they paid out and what they took in. That difference is the vig, and it's structural. You can never make it go away. You can only minimize how much of it you pay.

2. Why –110/–110 equals 4.76% vig

The standard NFL ATS line is –110 on each side. You risk $110 to win $100, on both the favorite and the underdog. Why does this little asymmetry add up to a 4.76% vig? Walk through the math:

The book's published prices imply a 104.76% probability across both outcomes — a logical impossibility, but a financial inevitability. That extra 4.76% is the book's edge per dollar bet, assuming balanced action.

An important nuance: 4.76% is the book's margin on the total handle, but the per-side cost to you as a bettor is roughly half that. As a bettor wagering on one side at a time, you're effectively paying ~2.38% in juice on each individual bet, which is why your breakeven win rate climbs from 50% to 52.38%.

3. Stripping vig from any line

To know whether a bet has actual value, you need to know what the true probability of the event is — not what the book's juiced price implies. Removing the vig from a two-sided line is straightforward:

Example. The Chiefs are –180 favorites and the Broncos are +160 dogs. Implied probabilities:

Now you have the market's true estimate, before commission. If you've independently estimated Chiefs at 67% and the no-vig price says they're 62.6%, you've got a genuine value bet. If your number is 60% and the no-vig says 62.6%, the market disagrees with you — pass.

4. How vig varies across markets

Not all sportsbook markets carry the same juice. The most heavily-bet and most efficient markets carry the lowest vig; the markets where books have pricing power (or large risk) carry significantly more.

This table is a sharp signal about where to focus and where to avoid. The markets where you can most reliably win are the ones where vig is lowest, because the market is hardest to beat anywhere else. The markets that "feel like" easy value (futures, exotic parlays) often hide vig levels that make consistent profit mathematically near-impossible.

5. Asymmetric vig and where the book hides its margin

Vig isn't always split evenly between two sides. Books shift juice to one side when they need to encourage action on the other or when they have a strong opinion about where action will land. A line like –115 / –105 still totals about 4.5% vig — but the side priced at –115 carries dramatically more of it than the side at –105.

This matters because the side with lighter juice is, by definition, the better-priced side relative to the no-vig fair line. If you'd take either side on a hunch, take the –105 one. If you'd take the –115 side, demand an even bigger edge to justify the premium price.

You'll also see asymmetric pricing on totals near a key whole number. When a total has been buy-back action all week from one direction, the book may post Over 47 at –120 and Under 47 at +100 — pricing in the imbalance rather than moving the number itself. The Under at +100 is significantly closer to fair value than the Over at –120.

6. Reduced-juice books and the long-term math

A small handful of sportsbooks specialize in reduced juice — pricing both sides of major markets at –105/–105 instead of –110/–110. The vig math is straightforward:

That's roughly half the vig of a standard market. Your breakeven win rate drops from 52.38% to 51.22%. Over thousands of bets, this is the single largest leverage point most bettors never pull.

The tradeoff: reduced-juice books typically have lower limits, fewer promotions, and less polish. They're not where you want to put 100% of your action. They are where you want to take a meaningful portion of it, especially on bets where you're confident the line itself is sharp at multiple books and you're just looking for the cheapest commission.

7. The compounding cost over 1,000 bets

One bet at –110 instead of –105 costs you about $2.40 per $100 wagered in expected loss difference. Single bet, no big deal. But scale it up:

These numbers assume zero edge — a 50/50 bettor whose only difference is the price they paid. A bettor with actual handicapping skill turns these savings into pure ROI on top of their edge. The 4.76% vig at –110 is roughly equal to the entire long-term ROI of a sharp bettor — meaning vig isn't a small input, it's the dominant cost a winning bettor is fighting against.