No-vig prices and implied probability, worked through

Implied probability is the chance of winning that a price represents. For negative American odds, divide the odds by the odds plus 100, ignoring the minus sign: -150 implies 150 / 250 = 60%. For positive odds, divide 100 by the odds plus 100: +130 implies 100 / 230 = 43.48%.

It is the break-even rate. A bet at -150 has to win more than 60% of the time to make money over many bets. Comparing that number with your own estimate is the whole decision.

Add the implied probabilities of both sides of a market and you get more than 100%. At -110 on both sides of a spread, each side implies 52.38%, for a total of 104.76%. The extra 4.76% is the vig, or juice: the book's margin.

That margin means the posted price is not the market's fair estimate. It is the fair estimate plus the book's cut, so judging a bet against the raw price sets the bar too high on both sides.

The simplest method divides each side's implied probability by the total. Take a moneyline of -150 and +130. The raw probabilities are 60% and 43.48%, which sum to 103.48%. Divide each by 1.0348 and the fair probabilities are 57.98% and 42.02%. Those add to 100%.

Convert back to odds if you want a fair price. 57.98% is about -138, and 42.02% is about +138. That pair is the no-vig line: the price each side would carry with no margin.

This proportional method is an approximation. Books often take more of their margin from the longshot side, so other methods shift the fair price slightly toward the favourite. For most two-way markets the difference is small. For longshots and futures it can matter.

Compare your estimate with the no-vig probability, then check that the price you can actually bet clears your estimate too. If you rate a side at 60% and the no-vig number is 57.98%, you see more than the market does. You still have to bet at -150, which needs 60%, so the edge is gone at that price. A better price at another book could bring it back.

Measure your closing line value against the no-vig close as well. That way you compare yourself with the market, not with the book's margin.

The same arithmetic works in any format. For decimal odds, implied probability is 1 divided by the odds: 1.91 implies 52.36%. For fractional odds such as 6/4, divide the second number by the sum of both: 4 / 10 = 40%. Convert every price to a probability first and the formats stop mattering.

Soccer moneylines usually have three outcomes: home, draw and away. Remove the vig the same way, across all three. Say home is +150 (40.00%), draw is +240 (29.41%) and away is +190 (34.48%). They sum to 103.89%. Divide each by 1.0389 and the fair probabilities are 38.50%, 28.31% and 33.19%, which add to 100%.

Three-way markets usually carry a larger total margin than two-way ones, so removing it matters more. Comparing a three-way price with a two-way estimate, without accounting for the draw, overstates every side.

Our models de-vig the market before comparing it with their own probability, and the edge on each pick is measured against that de-vigged market. Our how-it-works page walks through that pipeline, from the odds we collect to a graded pick. The no-vig method there is a model choice, and a different method would give slightly different edges.