What Is Vig in Betting? How to Calculate Vigorish & Find True Odds
What is vig in betting? Learn how to calculate vig with 3 methods, see how hold varies across 4 market types, and strip it from any line with our free de-vig calculator.
What is vig and why it matters
Every time you place a bet, you pay a fee. Sportsbooks call it vig (short for vigorish). You will also hear it called juice, hold, or margin. Prediction markets call it fees or spread. The word changes. The math does not.
Vig is the built-in margin that ensures the house profits regardless of outcome. It is the reason a standard coin-flip bet is not priced at +100/+100 (even money on both sides). Instead, sportsbooks price it at -110/-110. You pay $110 to win $100 on a 50/50 proposition. That $10 gap is the vig, and it is the single biggest reason most bettors lose money.
Understanding vig is not optional. It is the first step in the betting math pipeline. You cannot calculate expected value without first stripping the vig from the line to find the true probability underneath. And you cannot find an edge if you do not know how much the house is charging you.
How to calculate vig: the book sum method
The most direct way to measure vig is the book sum (also called the overround). Add up the implied probabilities of all outcomes in a market. If the total exceeds 100%, the excess is the vig.
Worked example: standard NFL spread
A market is priced at -110 on both sides.
Step 1: Convert each side to implied probability. (The odds converter does this instantly for any format.)
For American odds, the formula depends on the sign:
- Negative odds: Implied Probability = |odds| / (|odds| + 100)
- Positive odds: Implied Probability = 100 / (odds + 100)
Side A at -110: 110 / (110 + 100) = 110 / 210 = 52.38% Side B at -110: 110 / (110 + 100) = 110 / 210 = 52.38%
Step 2: Add the implied probabilities.
Book sum = 52.38% + 52.38% = 104.76%
Step 3: The excess over 100% is the overround.
Overround = 104.76% - 100% = 4.76%
That 4.76% is the vig baked into this market. The probabilities the sportsbook presents add up to more than 100%, which is mathematically impossible for the actual outcomes. The extra percentage is the house's cut.
The hold percentage
The hold percentage converts the overround into a more intuitive number: how many cents the book keeps per dollar wagered.
Hold = 1 - (1 / book sum)
For our -110/-110 market:
Hold = 1 - (1 / 1.0476) = 1 - 0.9546 = 4.54%
For every $100 wagered across both sides of this market, the sportsbook expects to keep $4.54. The hold calculator computes this instantly for any market you enter.
How vig varies across sports and market types
Not all markets charge the same vig. The pattern is consistent: the more obscure, complex, or low-volume the market, the more vig the sportsbook charges.
| Market Type | Typical Book Sum | Approx. Hold | Example Odds |
|---|---|---|---|
| NFL spread | 104.8% | 4.5% | -110 / -110 |
| NFL moneyline | 105-108% | 5-7% | -180 / +155 |
| NBA totals | 105-107% | 5-6.5% | -108 / -112 |
| NBA player props | 108-115% | 7-13% | -130 / +100 |
| 3-leg parlay | ~115% | ~13% | Combined |
| Niche props | 112-125% | 11-20% | Varies |
A few things jump out from this table.
Mainline spreads and totals carry the lowest vig because the volume is highest and the market is most efficient. Books compete on these lines, which keeps the margins thin.
Player props are where sportsbooks make their money. A book sum of 112% means you are paying roughly three times the vig of a standard spread. The inefficiency cuts both ways. There is more vig, but there is also more opportunity for edge because these lines are set with less precision.
Parlays compound the vig across every leg. Each leg carries its own overround, and when you multiply them together, the total vig snowballs. A 3-leg parlay can easily carry 13-15% total hold even if each individual leg is priced at standard -110. The parlay math breakdown walks through exactly how this compounding works.
Vig on prediction markets
Prediction markets like Kalshi and Polymarket use order books instead of fixed odds. But the vig principle is identical. If "Yes" contracts trade at $0.55 and "No" contracts trade at $0.50, the combined price is $1.05. That extra $0.05 is the spread, which is prediction market vig.
Worked example: Kalshi market with fees
A Kalshi market on "Will the Fed raise rates in March?" is priced at Yes $0.62 / No $0.43.
Book sum = $0.62 + $0.43 = $1.05, or 105%
The overround is 5%. On top of this spread, Kalshi charges an explicit fee of roughly 7% on profits from winning trades. So the true cost of trading this market is the spread vig plus the platform fee.
If you buy Yes at $0.62 and it resolves Yes, your gross profit is $0.38 per contract. After Kalshi's 7% fee on that profit: $0.38 x 0.93 = $0.3534 net. Your effective purchase price, adjusted for all costs, is higher than the $0.62 sticker. The prediction market fee calculator handles this math automatically.
Polymarket operates differently. No explicit trading fee, but the vig lives in the bid-ask spread. Either way, there is a cost. Read more in the prediction market fees guide.
Why vig is the reason most bettors lose
Here is the math that most bettors never calculate. On a standard -110 line, both sides imply a 52.38% probability. That means you need to win 52.38% of your bets just to break even.
Most recreational bettors win roughly 50% of their bets. On a -110 line, a 50% win rate produces:
- 50 wins x $100 profit = $5,000
- 50 losses x $110 loss = $5,500
- Net: -$500 on 100 bets
That $500 loss is not because the bettor is wrong. A 50% win rate on a 50/50 proposition is exactly correct. The loss comes entirely from the vig. You do not need to be wrong to lose money betting. You just need to be not right enough to overcome the built-in tax.
This is why expected value matters more than win rate. A bettor winning 48% of their bets at +150 is making money. A bettor winning 51% at -110 is losing money. The vig determines the threshold, and ignoring it means you are playing a game with invisible costs.
How to strip the vig and find true odds
De-vigging is the process of removing the bookmaker's margin to find the true implied probability. This is the foundation of finding edge. Once you know the true probability, you can compare it against the odds available to you and calculate whether a bet is +EV.
Worked example: de-vigging a moneyline
An NFL moneyline is priced at -180 / +155.
Step 1: Convert to implied probabilities.
- -180: 180 / 280 = 64.29%
- +155: 100 / 255 = 39.22%
Step 2: Book sum. 64.29% + 39.22% = 103.51%
Step 3: Multiplicative de-vig (simplest method).
- True probability of favorite: 64.29% / 1.0351 = 62.11%
- True probability of underdog: 39.22% / 1.0351 = 37.89%
Those de-vigged probabilities now sum to 100%. The favorite's true implied probability is 62.11%, not the 64.29% the sportsbook presents. If another book offers you the favorite at odds implying less than 62.11%, you are getting a better price than the market's best estimate.
The de-vig calculator runs this across seven different methods, including Shin and power models that account for favorite-longshot bias. For most two-way markets, the multiplicative method is sufficient. For multi-way markets with longshots, Shin or power methods are more accurate. The complete de-vig calculator guide walks through all 7 methods with worked examples and explains when each one gives you the most accurate result.
Platform-specific vig: how the cost varies by where you bet
The vig you pay depends on which platform you use and which market type you trade. Here is what vig looks like across the major platforms in 2026.
Traditional sportsbooks (DraftKings Sportsbook, FanDuel Sportsbook, BetMGM) price mainline spreads and totals at -110/-110. The hold is 4.5%. Player props carry wider margins, often 8-15% hold. Parlays compound the vig from each leg.
DraftKings Predictions charges $0.02 per contract per side through CME. On a $0.50 contract, that is 4% round-trip. The bid-ask spread adds another 2-5% depending on liquidity. Total effective vig: 6-9% on most markets.
Kalshi uses a taker fee of roughly 7% x p x (1-p), where p is the contract price. A $0.50 contract pays the maximum fee percentage. A $0.90 contract pays less because the profit potential is smaller. Spread vig adds 3-5% on top. Total effective vig: 5-10% depending on the price point.
Polymarket charges no explicit trading fee for most users. All the vig lives in the bid-ask spread, which ranges from 1-2% on high-volume markets (presidential elections) to 8-12% on thin markets (niche crypto events). The Kalshi vs Polymarket comparison breaks down how these fee structures compare at different contract prices.
Robinhood routes through Kalshi with a $0.01-0.02 per contract fee. The spread is often slightly wider than Kalshi's native order book because Robinhood pulls from the same liquidity pool with an extra fee layer.
FanDuel Predicts partners with CME at $0.01 per contract per side. The markup beyond the exchange fee is not publicly disclosed, but effective spreads suggest total vig of 5-8%.
The pattern across platforms: explicit fees are easy to measure, but spread vig is where the real cost hides. Use the prediction market fee calculator to see the total cost on any platform before you trade. And use the de-vig calculator to strip the spread from any market to find the true price underneath. The de-vig calculator guide explains which of the 7 methods to use for different market types.
Vig is not a concept to understand once and forget. It is the first filter in every betting decision. The full pipeline: strip the vig to find true probability, use that probability to calculate EV, then size your bet with the Kelly Criterion. Skip the first step and every downstream calculation is wrong.
The de-vig calculator and hold calculator are the starting point. Use them on every market before you calculate anything else. The vig is always there. The only question is whether you see it.
Frequently asked questions
- What does vig mean in sports betting?
- Vig (short for vigorish) is the fee a sportsbook charges on every bet. It is built into the odds as an overround. On a standard -110/-110 market, the vig creates a 4.5% hold, meaning the book keeps $4.50 of every $100 wagered across both sides.
- How much vig do sportsbooks charge?
- It varies by market type. NFL spreads carry roughly 4.5% hold. Player props can reach 13%. Parlays compound vig across legs and often exceed 15%. The more obscure the market, the higher the vig.
- Is vig the same as juice?
- Yes. Vig, juice, margin, hold, and overround all describe the same concept. They are the bookmaker's built-in fee. Different bettors and platforms use different terms, but the math is identical.
- Do prediction markets charge vig?
- Yes. On order-book platforms like Kalshi and Polymarket, vig shows up as the bid-ask spread. If Yes and No prices sum to more than $1.00, the excess is vig. Kalshi also charges explicit fees on winning trades, typically 5-10% of profit.
- How do I remove vig from a betting line?
- Convert each side to implied probability, sum them to get the book sum, then divide each side's probability by the book sum. This is the multiplicative de-vig method. For more precision, use Shin or power methods. The de-vig calculator handles all seven methods automatically.