The vig, also called juice or margin, is the sportsbook's cut, built into the odds. When both sides of a bet are -110, each implies 52.4%, adding up to 104.8% instead of 100%. That extra 4.8% means the book keeps about 4.5% of all money bet on that market over time, and you need to win 52.4% of -110 bets just to break even.
Key points
- Add the implied probabilities of every side: anything above 100% is the margin.
- Hold (the share of money the book keeps) at -110/-110 is 4.55%.
- Divide each side by the total to remove the vig and get the fair probability.
How to calculate the vig
Convert each side to implied probability (see odds explained), then add them:
| Market | Side A | Side B | Total | Fair A | Fair B |
|---|---|---|---|---|---|
| -110 / -110 | 52.4% | 52.4% | 104.8% | 50.0% | 50.0% |
| -150 / +130 | 60.0% | 43.5% | 103.5% | 58.0% | 42.0% |
The “fair” columns divide each side by the total, which removes the margin. The implied probability calculator does this for you.
Break-even at common prices
| Odds | Break-even win rate |
|---|---|
| -105 | 51.2% |
| -110 | 52.4% |
| -115 | 53.5% |
| -120 | 54.5% |
Why it matters
The vig is why picking winners half the time loses money, why better prices matter so much, and why parlays, which charge it on every leg, are so hard to beat. In FakeBet's own data for September 2026, straight bets won 51.7% of the time: close to the break-even point at typical prices, which is exactly what the vig predicts for a crowd of casual bettors (full report).
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