Implied probability and no-vig odds, explained

Every betting price implies a probability. Add up a sportsbook's implied probabilities for every outcome of a market and you'll get more than 100%. The excess is the sportsbook's margin, often called the vig or juice. Strip it out and you get no-vig (fair) probabilities: the sportsbook's best estimate of what will happen, before its cut.

From odds to implied probability

The odds converter does these conversions for you.

Measuring the margin

Take a common market where both sides are priced -110:

• Each side implies 110 ÷ 210 = 52.38%.
• Together: 104.76%. The overround is the 4.76% above 100%.
• The sportsbook's theoretical hold (its expected share of money wagered, if action is balanced) is 1 − 1 ÷ 1.0476 = 4.55%.

Overround and hold describe the same margin in different ways, so check which one a source means.

Removing the vig

The simplest method, and the one most calculators use, is proportional normalization: divide each implied probability by their total.

Example: Team A -150, Team B +130.

The sportsbook's own estimate, without its margin, is roughly 58/42. Try it with the no-vig calculator.

Why the method matters

Proportional normalization assumes the margin is spread in proportion to each side's probability. That's an assumption, not a fact about how sportsbooks price. Many researchers use it because it's simple, but it isn't the only option: Shin's procedure, for example, models a bookmaker setting prices against a mix of ordinary bettors and better-informed "insiders," and there's an open debate about which method to use.^[1]

For everyday two-way markets priced near even, the methods give similar answers. They diverge more for heavy favourites, longshots and markets with many outcomes.

Which market to de-vig

No-vig odds are only as good as the market they come from. A sportsbook with low limits that adjusts slowly can be consistently off; de-vigging its prices just gives you a precise version of a poor estimate. Positive-EV bettors usually de-vig a market they consider sharper (higher limits, quick to move) and compare other sportsbooks' prices against it. See What is positive expected value (+EV) betting?.