No-Vig Calculator

How to use it

1. 1 Pick a 2-way market (spread, moneyline, total) or a 3-way market (win, draw, win).
2. 2 Choose your odds format, then type the odds the book offers on every side.
3. 3 Read the fair probability and fair odds for each side, plus the hold the book is charging.

What no-vig odds are

A sportsbook prices every side of a market a little worse than the true chance, so the implied probabilities add up to more than 100%. That excess is the overround. Vig and juice are the everyday words for the book's cut in general, and hold is the share of the money staked that the book keeps when action is balanced. For -110 on both sides the implied probabilities total 104.76%, the overround is 4.76% and the hold is 4.55%. No-vig odds, or fair odds, are the same prices with that excess scaled back out, so the probabilities total exactly 100%.

Fair odds are useful because they are a better estimate of what the market really thinks than the posted price. If you can bet at a price better than the fair odds, and the fair odds are close to the true chance, the bet has positive expected value. If not, the book is keeping an edge on you.

How the calculation works

This calculator uses the multiplicative method, also called proportional. It converts each price to an implied probability, adds them up, then divides each probability by that total so they sum to exactly 100%. Fair decimal odds are one divided by the fair probability.

Other methods exist, including additive (subtract an equal slice from each side), power, and Shin. They agree on an even market but give slightly different answers on a lopsided one, such as a heavy favourite against a long shot, because they spread the book's cut differently. None is the single correct answer; the multiplicative method is the most common and the easiest to check by hand.

Hold here is 1 minus 1 divided by the total of the implied probabilities. It is the share of the money wagered that the book would keep if action were perfectly balanced.

Worked example

A book offers -200 on the favourite and +170 on the underdog. The implied probabilities are 66.67% and 37.04%, which add up to 103.70%. Dividing each by 103.70% gives fair probabilities of 64.29% and 35.71%.

The fair odds are -180 on the favourite (decimal 1.56) and +180 on the underdog (decimal 2.80). The hold is 3.57%. If you could get the underdog at +190 or better, you would be beating the fair price.

The formula

Frequently asked questions