MargusKey takeaways - Vig, juice, margin and overround are names for the same thing: the bookmaker's built-in edge. - It shows up as implied probabilities that add up to more than 100%. - -110 / -110 means a 104.76% book, roughly a 4.5% hold. - Three-way football markets and futures usually carry more margin than two-way US markets. - You can't avoid vig, but you can reduce what you pay by comparing prices.
Glossary
- Vigorish (vig): US term for the bookmaker's commission.
- Juice: US slang for the same thing.
- Overround: UK/European term; the total implied probability above 100%.
- Bookmaker margin / hold: the percentage of total stakes a book expects to keep if action is balanced.
- Book: the full set of prices for one market.
- Fair odds / no-vig odds: prices with the margin removed.
What is vig and why does it exist?
A sportsbook is a business. If it priced a true coin flip at evens (+100 / 2.00) on both sides, it would make nothing in the long run. Instead it shades both prices, to -110 (1.91) for example, so that if it takes equal money on each side, it pays out less than it took in.
In the UK and Europe the same idea is called the overround: the "book" is made over 100%. Whatever the name, it is the reason most bettors lose over time, and the single biggest cost you can control.
How to calculate vig on a two-way market
Step 1: convert to implied probability
Use the formulas in our implied probability guide. For -110: 110 ÷ 210 = 52.38%.
Step 2: add up all outcomes
52.38% + 52.38% = 104.76%. The overround is 4.76%.
Step 3 (optional): convert to hold
hold = 1 − (1 ÷ total) → 1 − (1 ÷ 1.0476) = 4.55%.
That means if a book takes $110 on each side of a -110 / -110 line, it collects $220 and pays $210 to the winner, keeping $10: 10 ÷ 220 = 4.55%.
Worked example: NFL moneyline
Eagles -180, Giants +155:
- Eagles: 180 ÷ 280 = 64.29%
- Giants: 100 ÷ 255 = 39.22%
- Total: 103.51% → hold ≈ 3.39%
Now imagine another book has the Giants at +165 (37.74%). Take the Eagles at the first book and the Giants at the second, and the combined book is 64.29% + 37.74% = 102.03%. Just by shopping one side, you have cut the margin you face by more than a third. That is the arithmetic behind line shopping.
How to calculate overround on a three-way football market
Arsenal v Chelsea, match result:
| Outcome | Fractional | Decimal | Implied |
|---|---|---|---|
| Arsenal | 10/11 | 1.91 | 52.36% |
| Draw | 13/5 | 3.60 | 27.78% |
| Chelsea | 16/5 | 4.20 | 23.81% |
| Total | 103.95% |
Overround: 3.95%. Hold: 1 − 1 ÷ 1.0395 ≈ 3.80%.
Three-way markets spread the margin over three outcomes, and the draw can carry a disproportionate share. Always check the full book, not just the side you like.
Where the vig is higher (and lower)
Margins vary by market and operator. As a general pattern, which you can verify yourself with the method above:
- Main markets on popular games (NFL spreads, Premier League match result) tend to be the most competitive, because operators compete hardest for them.
- Props, same-game parlays and niche leagues usually carry higher margins.
- Futures and outrights (Super Bowl winner, Premier League title) often have very large overrounds, because the margin is spread across many outcomes.
- Parlays/accumulators multiply margins. Each leg carries its own vig, and they compound.
- Exchanges and prediction markets charge commission or trading fees instead of shading prices, and there is a bid-ask spread. Depending on price and liquidity, the effective cost can be lower or higher than a sportsbook's. See prediction markets vs sportsbooks.
Why vig matters so much
At -110, the break-even win rate is 52.4%. Picking winners at 51% feels good, but at standard juice it loses money over time. Lower the price to -105 and break-even drops to 51.2%; at +100 it is exactly 50%.
Put another way: the margin is a tax on every bet. A good bettor's edge is often small, and paying an extra point or two of vig can turn a winning approach into a losing one. You can't control results, but you can control the price you accept.
Reduced-juice and boosted lines
Some sportsbooks occasionally offer reduced-juice lines (e.g. -105 / -105) or price boosts. These can be genuinely good value, but read the terms: boosts often come with maximum stakes, and a boosted parlay may still carry more margin than a single straight bet at the best available price. Calculate the implied probability yourself before assuming it is a deal.
How vig compounds in parlays and accumulators
Every leg of a parlay (or accumulator, in UK terms) carries its own margin, and the margins multiply. Take a three-leg NFL parlay where every leg is -110 / -110. Each leg's fair price is +100 (2.00), so a fair three-leg parlay would pay 2.00 × 2.00 × 2.00 = 8.00 (+700). At -110 per leg, the parlay pays 1.91 × 1.91 × 1.91 ≈ 6.96 (+596).
Convert both to implied probability: the fair parlay is 12.5%, the priced parlay is about 14.4%. The book's edge has grown from roughly 4.5% on a single to well over 10% on the parlay. Add more legs and it keeps growing. Same-game parlays are priced with their own correlation adjustments, which usually adds further margin.
That doesn't mean parlays are always wrong, and a boosted parlay can occasionally be good value, but it does mean you should know what you are paying. The same arithmetic applies to a Saturday football acca: five 1X2 selections, each with a 4–5% overround, compound into a much larger edge for the bookmaker.
Converting no-vig prices back to odds
Once you've removed the margin (divide each implied probability by the total, as shown in our implied probability guide), turn the fair probability back into odds with fair decimal = 1 ÷ fair probability. In the NFL moneyline example above, the Eagles' 64.29% becomes about 62.1% fair, or roughly 1.61 (-164); the Giants' 39.22% becomes about 37.9%, or roughly 2.64 (+164). Any price better than those fair numbers, at any operator, is beating the market's own estimate.
Common mistakes
- Only looking at your side. Vig is a property of the whole market; check both sides to see how much you are paying.
- Ignoring the draw. In football, a 1X2 market's margin includes the draw.
- Assuming all books charge the same. They don't, and the gap can be meaningful on the same game.
- Treating fees as free. Prediction market fees and exchange commission are a form of vig.
Expert tips
- Calculate the overround before you bet. It takes seconds and tells you how competitive a price is.
- Build your own "best-of" book. Take the best price on each outcome across operators; the combined total is the lowest margin available to you.
- Be selective with parlays. Each leg adds margin; singles at the best price are usually cheaper.
- Use no-vig prices as a benchmark. Remove the margin from a competitive market to estimate fair odds, then look for better-than-fair prices elsewhere.
- Check how comparisons are made. Our methodology explains how Margus lines up prices from different operators.
Pay less vig with Margus
Margus shows DraftKings, BetRivers, theScore Bet, Kalshi and Polymarket prices next to each other so you can find the lowest-margin price on every side. Start with all odds, drill into NFL odds or soccer odds, and see how fees on prediction markets compare.
*Margus is an odds-comparison and research site and does not accept bets. Lower margins improve your price, not your odds of winning. Bet responsibly and see our responsible gaming page for help and resources.*
Frequently asked questions
What is the vig in sports betting?
The vig (short for vigorish), also called juice or margin, is the commission a sportsbook builds into its odds. It is why both sides of an even contest are priced below even money, such as -110 / -110.
How do you calculate vig?
Convert each outcome's odds to implied probability and add them up. The total above 100% is the overround. For the bookmaker's hold, use 1 − (1 ÷ total).
Is -110 standard vig?
-110 on both sides is a common US price for spreads and totals. It equals a 104.76% book, or about a 4.5% hold.
What is the difference between overround and vig?
Overround is the total implied probability minus 100% (e.g. 4.76%). Hold or vig is often expressed as the share of money the bookmaker expects to keep (e.g. 4.55%). They describe the same margin in two ways.
Do prediction markets have vig?
Prediction markets like Kalshi typically charge trading fees rather than building a margin into prices, and there is a bid-ask spread between buyers and sellers. Both act as a cost similar to vig.
How can I pay less vig?
Compare prices across operators and bet with whoever has the best number. The best available price across several books often has a much lower combined margin than any single book.