What is Vig in Sports Betting?

Vig Explained in Detail

Vig and juice are interchangeable terms that describe the sportsbook's built-in commission. The word vigorish comes from Yiddish and has been used in gambling for over a century. In modern sports betting, vig and juice are the most common shorthand terms.

The vig is what makes sports betting a negative-sum game for the average bettor. If you flip a coin and the sportsbook prices both heads and tails at -110, you are paying a 4.5% tax on every flip. Over time, the average bettor will lose money at a rate approximately equal to the vig.

To calculate the true implied probability from odds with vig, you need to remove the vig from both sides. If both sides of a bet are -110, the implied probability for each side is 52.4%. But since both sides cannot each have a greater than 50% chance, the extra 4.8% (52.4% + 52.4% = 104.8%) represents the vig. The true probability for each side is closer to 50%.

Professional bettors obsess over the vig because it directly impacts their bottom line. Reducing the effective vig by even 1% through line shopping can mean the difference between a profitable year and a losing one. Some sharp bettors exclusively use sportsbooks that offer reduced vig or bet on exchanges where the vig is lower.