Once you can see the vig in a two-sided market (covered in what the vig is), the next useful move is removing it — which gives you the market’s real consensus probability, sometimes called the no-vig price or fair price.

The idea

Take both sides of a market, convert each to an implied probability, and normalize them so they add up to exactly 100% instead of (say) 104.8%. What’s left is the market’s best estimate of the true probability of each outcome, with the sportsbook’s margin stripped out.

A worked example

Say a spread is priced at −110 on both sides: 52.38% implied on each side, summing to 104.76%. Divide each side by that total:

  • 52.38% ÷ 104.76% = 50.0%
  • 52.38% ÷ 104.76% = 50.0%

Symmetric market, so the fair price lands at an even 50/50 — as you’d expect. It gets more useful on a lopsided market. If one side is −140 (58.3% implied) and the other is +120 (45.5% implied), that totals 103.8%. Normalized: 56.2% and 43.8%. That 56.2% is a meaningfully cleaner estimate of the true probability than the raw 58.3% the price alone suggested.

What it’s actually useful for

A single book’s price doesn’t tell you much in isolation — is −140 a good number, or is it padded? The fair price, built from the wider market (OctopusOdds blends this from multiple sportsbooks and, where available, no-fee prediction markets), gives you a reference point to measure any individual book’s price against. A book offering a number noticeably better than the fair price is giving you more than the market consensus says the bet is worth; a number noticeably worse means that particular book is charging extra vig on that specific line.

The honest caveat

A no-vig fair price is a market consensus, not a guarantee of the true probability. It can still be wrong — markets misprice things, especially on thinner markets with less betting volume behind them. Treat it as the best available reference point, not an oracle.

It’s also the foundation for the metric in the next guide: once you know the fair price at the moment you bet, you can compare it to the fair price right before kickoff — which is exactly what closing line value measures.