Price mechanics8 min read

Sportsbook Vig and No-Vig Probability

Vig—also called juice, hold, or overround—is the margin embedded in a sportsbook market. Removing that margin does not reveal objective truth, but it creates a cleaner estimate of what the market price is saying.

Written and reviewed by the TailGate Research DeskUpdated September 11, 2026

What to remember

The vig is embedded in the prices rather than shown as a separate checkout fee.
A two-way market’s raw implied probabilities usually add to more than 100%.
A simple no-vig estimate normalizes both sides so they total 100%.
Different removal methods can produce different estimates in uneven markets.

The familiar -110 / -110 example

At -110, each side carries a raw implied probability of about 52.38%. Add both sides and the market totals about 104.76%. The amount above 100% is the overround in this simple two-outcome view.

If the market were perfectly balanced and you used proportional normalization, dividing each 52.38% estimate by 104.76% produces 50% on each side.

Overround = sum of raw implied probabilities − 100%

How proportional de-vigging works

First convert every outcome to raw implied probability. Then divide each probability by the sum across all mutually exclusive outcomes. The normalized results total 100%.

For a market priced -120 and +100, the raw probabilities are about 54.55% and 50%, totaling 104.55%. Proportional normalization produces approximately 52.17% and 47.83%.

No-vig probability = raw implied probability ÷ total market probability

Why no-vig is an estimate

Proportional normalization assumes the margin is distributed proportionally. Sportsbooks may shade a favorite and underdog differently, and long-shot markets can behave differently from tight two-way markets. More advanced methods make different assumptions about how the margin is allocated.

That means ‘fair probability’ should be presented with its method and source market. A precise-looking number without that context can imply more certainty than the calculation supports.

Using no-vig probability in a slip review

No-vig estimates are most useful when you compare the same event, market, selection, and line. A consensus across several current books can reduce dependence on one book’s inventory or customer mix.

The estimate becomes less reliable when the market is stale, suspended, thinly traded, or matched to a different line. Good analysis identifies those gaps instead of forcing a score.