Betting Education · 2026-07-27 · 10 min read
How to Calculate Vig in Sports Betting
To calculate vig in sports betting, convert each side of a line to its implied probability, add those two probabilities together, and subtract 100. The leftover percentage is the sportsbook's margin. On a standard -110/-110 point spread, that math works out to a 4.55% vig rate: the book keeps roughly $4.55 for every $100 in balanced action, before a single result is decided.
This guide walks through the formula step by step, with worked examples on NFL spreads, NBA totals, and MLB moneylines. If you want the background on what vig actually is and why it exists, start with the full vig explainer first.
Key Vig Numbers to Know
- Standard spread (-110/-110): 4.55% vig
- Reduced juice spread (-108/-108): 3.71% vig
- Typical range at legal US books on core markets: 4% to 6%
- Futures markets at major legal books: 10% to 20% or higher
- Fair odds (zero vig): implied probabilities sum to exactly 100%
- Break-even win rate at -110: 52.38%
- Break-even win rate at -108: 51.92%
The Vig Formula, Step by Step
Every sportsbook line implies a probability for each side. When you add those implied probabilities together, the total always exceeds 100%. That excess is the vig, also called juice, margin, or overround. The book is the only party guaranteed to profit regardless of which side wins, because the odds are set so both sides of any market sum to more than a fair coin flip.
Step one is converting American odds to implied probability. The formula depends on whether the line is negative or positive:
- Negative odds (favorite): Implied probability = |odds| divided by (|odds| plus 100), multiplied by 100.
- Positive odds (underdog): Implied probability = 100 divided by (odds plus 100), multiplied by 100.
Step two is calculating the vig rate from the total:
Vig rate = (sum of implied probabilities minus 100) divided by sum of implied probabilities, times 100
If the sum of implied probabilities equals 104.76%, the vig rate is (4.76 / 104.76) x 100 = 4.55%. That is the standard number on a -110/-110 line.
Example 1: NFL Point Spread (-110 / -110)
The most common line you will see across US sportsbooks. Both sides are priced at -110.
- Implied probability, favorite: 110 / (110 + 100) x 100 = 52.38%
- Implied probability, underdog: same line, same result = 52.38%
- Total implied probability: 52.38 + 52.38 = 104.76%
- Vig rate: (4.76 / 104.76) x 100 = 4.55%
In plain terms: the book is charging you $4.55 per $100 wagered, in expectation. You need to win 52.38% of your spread bets just to break even, not the intuitive 50% that a coin-flip market should require.
Example 2: NBA Total (-115 / -105)
Not all lines are symmetrical. Books sometimes shade one side to manage their own exposure, which changes the math slightly.
- Implied probability, over at -115: 115 / (115 + 100) x 100 = 53.49%
- Implied probability, under at -105: 105 / (105 + 100) x 100 = 51.22%
- Total implied probability: 53.49 + 51.22 = 104.71%
- Vig rate: (4.71 / 104.71) x 100 = 4.50%
The total vig here is similar to the -110/-110 baseline, but the line is not balanced. If you believe the true probability of each outcome is close to 50%, taking the under at -105 is meaningfully better value than taking the over at -115. Line shopping between books specifically for this kind of discrepancy is one of the most reliable low-effort edges a recreational bettor has.
Example 3: MLB Moneyline (-175 / +150)
Moneylines on heavy favorites look intimidating, but the overround calculation follows the same logic.
- Implied probability, favorite at -175: 175 / (175 + 100) x 100 = 63.64%
- Implied probability, underdog at +150: 100 / (150 + 100) x 100 = 40.00%
- Total implied probability: 63.64 + 40.00 = 103.64%
- Vig rate: (3.64 / 103.64) x 100 = 3.51%
Counter-intuitively, lopsided MLB moneylines can carry a lower vig rate than standard point spreads. The wide payoff gap between the two sides distributes the book's margin differently. This does not mean you should prefer them; the implied probability gap also means one side is a long shot. But it illustrates that vig rate and bet difficulty are separate questions.
What Is a Good Vig Percentage?
For standard two-sided markets like spreads and totals, below 5% is reasonable. Below 4.5% is good. Books that consistently post sub-4% margins on core NFL and NBA markets are genuinely offering better value, and the difference compounds over a full season of betting.
Futures markets operate in a different range. A 10% to 15% margin on pre-season championship futures is common even at the largest legal US books. Some props and specials sit higher. The key discipline is checking the margin on the specific markets you actually bet, not relying on a book's headline line as a proxy for all its pricing.
How Vig Compares Across Market Types
| Market | Typical Line | Implied Total | Vig Rate |
|---|---|---|---|
| NFL / NBA Spread | -110 / -110 | 104.76% | 4.55% |
| Reduced Juice Spread | -108 / -108 | 103.85% | 3.71% |
| Shaded NBA Total | -115 / -105 | 104.71% | 4.50% |
| Tight MLB Moneyline | -175 / +150 | 103.64% | 3.51% |
| Typical NFL Futures | Varies | 112% to 120% | 10.7% to 16.7% |
VigVerdict's Juice Check section in every full sportsbook review documents actual margins on NFL spreads, NBA totals, and MLB moneylines at the books we test. See the FanDuel vs DraftKings comparison and the Fanatics Sportsbook review for real-world pricing numbers at two of the largest US operators.
Why Vig Matters for Your Long-Term Results
At -110, you need to win 52.38% of bets to break even. At -108, that threshold drops to 51.92%. The difference is 0.46 percentage points per bet, which sounds trivial on any single wager. Across 500 bets over a season, it is the difference between a losing record and a profitable one for any bettor operating near the edge.
The practical implication is simple: for bettors without a strong statistical edge, minimizing vig is the single highest-return improvement available without needing any additional handicapping skill. You do not have to be a sharper analyst to pay less juice. You just have to shop lines between two or three books.
"Shopping for the best line is the equivalent of buying an index fund at a lower expense ratio. You do not feel it on any single bet, but compounded over years it is the most reliable edge a recreational bettor has access to. The vig is the price of admission. Your job is to pay as little of it as possible."
VigVerdict Editorial Methodology
Frequently Asked Questions
What does a 15% vig mean?
A 15% vig means the book's total implied probability across both sides of a market is 115%. The expected long-run cost to bettors is $15 per $100 in action. This level is uncommon on standard two-sided markets but appears on large futures pools, especially at offshore books. Legal US sportsbooks rarely post above 15% on major championship futures.
What does a 10% vig mean?
A 10% vig means the total implied probability sums to 110%, and bettors need to win roughly 55% of their bets just to break even at those odds. This level turns up on niche props, player specials, and some exotic wagers. Avoid markets with a consistent overround above 8% unless you have a very specific and verified edge on that exact market type.
What does a 7% vig mean?
A 7% vig means the implied total is 107%. It is higher than the standard spread market (4.55%) but lower than most futures. Some books post this range on same-game parlays or player props where pricing is less competitive. Bettors who mostly play these market types are paying about 50% more in margin than bettors who stick to core spread markets at standard lines.
How do I find the fair odds behind any line?
Divide each side's implied probability by the total implied probability. For -110/-110: each side's implied is 52.38%, the total is 104.76%. Fair implied probability for each side = 52.38 / 104.76 = 50.0%, which converts to even money (+100 in American odds). The book has added 4.55% vig on top of those fair 50/50 odds to arrive at -110 on both sides.
Is vig the same as the hold?
Not exactly. The hold is the percentage of total money wagered that the book keeps after settling bets, measured after the fact. Vig (or overround) is the margin built into the odds before any action is taken, a theoretical number. On perfectly balanced two-sided action the two converge. When one side attracts heavily lopsided betting, the book's actual hold can be higher or lower than the theoretical vig on that game.
Does vig differ between sportsbooks?
Yes, sometimes significantly. Some legal US books offer reduced-juice lines of -108 on spreads as a standard practice, while others consistently post -110 or worse. Futures margins vary more dramatically. Checking the vig on the specific markets you actually play, rather than assuming one book is always cheaper, is what matters in practice.
Last reviewed: July 2026. Vig rates and example lines reflect typical US legal sportsbook pricing as of this date and are updated annually.
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