Devigging Explained: How to Remove the Vig

What is the vig?

The vig (short for vigorish, also called juice or the overround) is the margin that sportsbooks build into their odds. It's their commission — the reason they profit regardless of which side wins.

On a fair coin flip, both sides should be priced at +100. But a sportsbook prices it at -110/-110, meaning you need to bet $110 to win $100 on either side. If they get equal action ($110 from each side = $220 total), they pay out $210 to the winners and keep $10.

The vig varies by market and sportsbook. Main markets (spreads, totals) typically carry 3-5% vig. Player props can carry 8-15%+ vig. Lower-liquidity markets tend to have wider margins because sportsbooks have less confidence in their pricing.

Why devigging matters

To find +EV bets, you need to know the true probability of an outcome. Sportsbook odds don't tell you the true probability — they tell you the vigged probability. Devigging removes the margin to estimate what the sportsbook actually believes the fair probability is.

Once you have a fair probability estimate, you can compare it to the odds at other sportsbooks. If Book A's devigged line implies a 40% true probability for the underdog, and Book B is offering +160 (which implies 38.5%), then Book B's price is below fair value — that's a potential +EV opportunity.

Devigging is the mathematical backbone of all positive expected value betting. Without it, you're guessing at probabilities instead of estimating them systematically.

Devig methods: additive, multiplicative, and power

There are several ways to remove the vig. Each method makes different assumptions about how sportsbooks distribute their margin across the two sides:

• Additive (equal margin): Assumes the sportsbook adds equal margin to both sides. You subtract the same percentage from each side's implied probability so they sum to 100%. This is the simplest method.
  Vigged: -150 (60.00%) / +130 (43.48%) = 103.48% total
  Overround: 3.48%
  Fair: 60.00% - 1.74% = 58.26% / 43.48% - 1.74% = 41.74%
• Multiplicative (proportional): Assumes margin is proportional to each side's probability. Larger probabilities absorb more vig. Divide each implied probability by the total overround.
  Vigged: -150 (60.00%) / +130 (43.48%) = 103.48% total
  Fair: 60.00% / 1.0348 = 57.98% / 43.48% / 1.0348 = 42.02%
• Power (Shin method): Assumes more vig is applied to the longshot side, which research suggests is what sportsbooks actually do (the favorite-longshot bias). This method uses an iterative calculation that applies more margin reduction to the favorite.

In practice, all three methods produce similar results on tight markets (low vig). The differences become meaningful on high-vig markets like player props. DawBets uses multiple devig methods and compares results across 20+ sportsbooks for more robust probability estimates.

Try it yourself: the devig calculator computes fair no-vig odds for two-way and three-way markets using multiplicative, additive, or power methods.

Worked example: devigging a real market

Let's devig a real NFL spread market and use it to evaluate a bet at another sportsbook.

In this case, the Bills at +100 is actually slightly -EV (close to fair). If DraftKings was offering Bills +3.5 at +105, the EV would flip positive. This is how devigging works in practice — it gives you a precise fair value to compare against every available price.

Sharp vs. soft books: which to devig from

Not all sportsbooks are equally useful for devigging. Sharp books (like Pinnacle, Circa, or Bookmaker) accept large bets from professional bettors, which forces their lines to be highly accurate. Their odds most closely reflect true probabilities.

Soft books (most US retail sportsbooks) cater to recreational bettors and are slower to move their lines. They may also shade their odds based on public bias — making popular teams slightly more expensive than they should be.

The best approach is to devig from sharp books to establish fair value, then look for bets at soft books where the price exceeds that fair value. DawBets compares odds from the full spectrum — sharp and soft — to identify where the genuine edges exist. You can explore these in the odds comparison tool.

Frequently asked questions