What is Vig (juice)?
The sportsbook's built-in margin. The gap between the sum of implied probabilities across all outcomes and 100%.
Also known as: vigorish, juice, overround
Sportsbooks set prices so that the implied probabilities across both sides of a market add up to more than 100%. The extra is the vig (or juice), and it is the book's expected gross margin. A standard −110 / −110 market has roughly 4.5% vig. To beat the book you need a model whose edge exceeds the vig on every bet you place.
Example
A market with both sides priced at −110 has 52.4% + 52.4% = 104.8% implied probability. The 4.8% above 100% is the vig.
Related terms
The probability of a result that a sportsbook's odds are pricing in. Calculated as one divided by the decimal odds.
Expected value (EV) is the average profit or loss a bet pays per dollar staked if you repeated it under the same odds and probability forever.
Comparing prices at multiple sportsbooks to bet the best available number on every play.
See vig (juice) applied to a real slate
NotaSportsGuru runs the math behind every published leg. Parlay of the Day, player props, match lines. With the model’s expected value and edge on every line.