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What Is Vig (Vigorish)? How Sportsbooks Make Money
Last Updated: March 4, 2026
Vig — short for vigorish and also called juice or hold — is the margin sportsbooks build into every line they offer. It is the reason a standard point spread lists both sides at -110 rather than +100, and it is the single largest factor separating profitable bettors from unprofitable ones over time.
Key Takeaways
- Vig is the built-in commission on every bet, typically 4-5% on standard sides and totals, and 8-15%+ on props and parlays.
- The formula is straightforward: sum the implied probabilities of all outcomes, subtract 100%, and the remainder is the overround that funds the book’s margin.
- Prediction markets replace traditional vig with explicit fee structures — Kalshi charges 7% on winnings, Polymarket roughly 2% — making cost comparison essential.
- At volume, even small vig differences compound dramatically: a bettor placing 1,000 wagers per year saves hundreds of dollars per percentage point of reduced hold.
- Our dataset of 149K historic games from 2007-2022 across six major sports shows average vig varies significantly by book and sport.
How Does Vig Work?
A sportsbook’s primary business model is not predicting outcomes — it is pricing both sides of a wager so that the combined implied probability exceeds 100%. That excess is the overround, and the effective margin extracted from it is the vig.
Consider the most common line in American sports betting: -110 on both sides of a point spread. A bettor must risk $110 to win $100. If the book takes equal action on both sides, it collects $220 in total wagers and pays out $210 to winners (their $110 stake plus $100 profit). The $10 difference is the vig.
This structure means the book profits regardless of which side wins, provided action is balanced. When action is imbalanced, the book takes on directional risk — but the vig still provides a cushion.
How Do You Calculate Vig?
The calculation requires converting odds to implied probabilities, summing them, and measuring the overround.
Step 1: Convert to implied probability. For American odds, the formula depends on sign:
- Negative odds: Implied probability = |odds| / (|odds| + 100)
- Positive odds: Implied probability = 100 / (odds + 100)
Step 2: Sum the implied probabilities.
Step 3: Calculate vig. Vig (%) = (Sum - 1) / Sum x 100
Worked Example: -110 / -110
| Step | Side A (-110) | Side B (-110) |
|---|---|---|
| Implied probability | 110 / 210 = 52.38% | 110 / 210 = 52.38% |
| Sum | 104.76% | |
| Overround | 4.76% | |
| Vig (hold) | 4.76 / 104.76 = 4.55% |
The true probability of each side is 50%, but the book prices each at 52.38%. That 4.76 percentage points of overround translates to a 4.55% hold on total handle.
For lines with different odds on each side — say -115 / +100 — the same process applies. Convert each side, sum, and calculate. Our vig calculator handles any odds format automatically.
How Does Vig Vary by Bet Type?
Not all bets carry the same margin. Books embed higher vig in markets where bettors are less price-sensitive or where sharp action is lighter.
| Bet Type | Typical Vig | Notes |
|---|---|---|
| NFL/NBA sides & totals | 4-5% | Most competitive market; heavy sharp action |
| MLB moneylines | 3-5% | Varies by matchup; lopsided games carry more |
| Player props | 8-15% | Less liquid, higher information asymmetry |
| Same-game parlays | 15-30%+ | Correlated outcomes priced with wide margins |
| Futures | 10-25% | Long-duration hold; early-season books widest |
| Live / in-game | 6-12% | Fast-moving; books widen to manage risk |
| Alternate lines | 6-10% | Off-market spreads carry extra premium |
Shopping across multiple books compresses effective vig. A bettor who consistently takes the best available line across three or four books can reduce their effective hold by 1-2 percentage points per wager — a material edge over thousands of bets. Our sportsbook comparison tool surfaces these differences.
How Does Vig Compare to Prediction Market Fees?
Prediction markets like Kalshi and Polymarket do not embed vig in the traditional sense. Their odds are set by market participants, not a bookmaker, so the overround in the order book reflects natural bid-ask spread rather than an imposed margin.
Instead, these platforms charge explicit fees:
- Kalshi: 7% of net winnings (no fee on losing positions). On a 50/50 bet, this equates to roughly 3.5% effective hold.
- Polymarket: No explicit fee on outcomes, but the CLOB spread typically runs 1-3%, functioning as an implicit cost.
This fee transparency is one reason prediction markets have attracted volume from bettors accustomed to sportsbook pricing. However, the total cost depends on win rate, position size, and whether you hold to expiry or trade out early. Our fee calculator models these scenarios.
For a full glossary of terms like overround, hold, and implied probability, see the prediction markets glossary.
Why Does Low Vig Matter at Volume?
For a casual bettor placing 20 wagers per season, the difference between 4.5% vig and 6% vig is negligible — a few dollars. For a serious bettor placing 1,000+ wagers per year at an average stake of $100, that 1.5 percentage point difference compounds to $1,500 in annual margin cost.
This is why professionals obsess over line shopping, reduced juice promotions, and platform fee structures. The how to read betting odds guide covers the mechanics of translating between formats, which is the prerequisite skill for comparing vig across books.
Track real-time odds movement and identify which books are offering the tightest lines on the Odds Reference dashboard.
FAQ
See the FAQ entries above for quick answers to the most common vig questions.