Sportsbooks bake in a margin called the vig (vigorish), also called the "juice" or "overround." On a 50/50 game, both sides are typically offered at -110 instead of +100. That extra ~5% is the book's profit.
Standard 50/50 line: Pistons -110 / Cavs -110 → both 52.4% implied → total 104.8% → vig = 4.8%
Enter both sides of a line. See the book's margin and the fair odds.
| Side | Your odds | Implied % | Fair odds (no vig) | True % |
|---|
Not all books charge the same vig. Pinnacle is the sharpest (lowest margin); recreational books charge more.
| Sportsbook | Typical vig on -110/-110 line | Notes |
|---|---|---|
| Pinnacle | ~2.5% | Sharpest, no US license, professionals' choice |
| BetOnline / Bookmaker | ~3-3.5% | Reduced juice ("-105/-105") |
| DraftKings | ~4.5% | US mass-market |
| FanDuel | ~4.5-5% | US mass-market, similar to DK |
| BetMGM | ~4.5-5% | Wider on player props |
| Caesars | ~4.5-5% | Similar to others |
It implies 52.4% probability. The fair line at 50/50 is +100 (or "even money"). The 2.4% gap is your cost to play.
Divide each side's implied probability by the total. If line is -110/-110 (52.4% + 52.4% = 104.8% total), true probabilities are both 52.4%/1.048 = 50%.
A -300 favorite implies 75%. If the opposite side is +250 (28.6%), total is 103.6% (3.6% vig). Always compare both sides to detect hidden margin.