No-vig fair odds & the hold
What the vig is, how the hold is baked into every market, and how removing that margin yields a fair price you can measure value against.
The margin baked into every price
Every sportsbook builds a margin into its odds. That margin goes by several names — the vig (short for vigorish), the juice, or the hold — and it is the reason the implied probabilities of a two-sided market add up to more than 100%. If a coin flip were priced honestly, both sides would pay even money and each implied probability would be 50%, summing to exactly 100%. A real book might price both sides at -110, where each side implies roughly 52.4%, summing to about 104.8%. That extra 4.8% is the hold: the book's built-in edge regardless of which side wins.
The hold is why betting at offered prices loses money on average. To find value you cannot compare a book's price against itself — you have to strip the margin out and recover what the price would be at a 0% hold, where the implied probabilities sum to exactly 100%. That stripped price is the no-vig fair odds.
From offered price to fair price
Removing the margin is called devigging. Conceptually, you take the implied probabilities a book is quoting, then rescale them so they sum to 100% instead of 104.8%. What remains is an estimate of the true probability of each outcome, free of the book's cut. Convert that probability back into odds and you have the fair price — the benchmark every +EV calculation measures against.
Market width
Not every fair price is equally trustworthy. Market width describes how far apart the sharpest books are on the same market. A tight, liquid market — a major-league moneyline, say — has many books clustered within a cent or two, so the fair price is sharp and confident. A wide market, such as an obscure player prop, has books scattered far apart, so the devigged fair price is noisier and the edge it implies is less certain. Width is a measure of how much to trust the number, not the number itself.
0% hold is the goal, not the reality
No real book offers 0% hold. The no-vig fair odds are a computed price — the line the market would settle on if you removed every book's margin — and it is only ever an estimate of the truth.
The specific methods SmartStake uses to remove the margin are covered in Devigging & fair value. For how the resulting fair price turns into a measurable edge, see Expected value & +EV betting.
- Odds, prices, expected value, conversion rates, and profit figures shown are estimates based on the last data we retrieved. They can change at any time — confirm the current price at the book before you bet, as odds may move and entry errors can occur.