# Fair Odds Calculator

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This fair odds calculator strips pairs of American odds into fair value implied probability and “no vig” odds. This calculation converts the odds into a form that is easier to understand by removing the expected sportsbook edge (otherwise known as vig or juice), and giving you the percent likelihood of each occurring as well as the odds you would expect if the sportsbook weren’t involved.

This calculator only works on 2-outcome events like moneyline or spread bets. If you have a win, lose or draw 3 way bet, you need the 3 Way Fair Odds Calculator. For a full description of the math behind the calculator see the article below. To use the fair odds calculator simply enter the American odds in the space provided and hit calculate to get the percent value.

## What Are Fair Odds And “The Vig”?

Fair odds are the chances of winning if the sportsbook didn’t add the “vig,” which is the sportsbook’s cut for taking the bet.

For example, a standard points spread bet will have -110 odds. That extra -10 is the vig. So, when you use the vig free calculator, the odds will be presented as if that vig wasn’t added. In the -110 example, the no vig calculator would show +100 odds and a 50% true probability.

Those are the “fair odds,” meaning you and the sportsbook have the same chances of winning a bet.

The equivalent would be a double or nothing bet on a coin flip. But no casino or sportsbook would take that wager, because doing so would mean they couldn’t guarantee long-term profits.

And, yes, they can mathematically guarantee long-term profits as long as they have enough people placing bets.

## How The Fair Odds No Vig Calculator Works

Fair Odds is more of guideline than a hard and fast measure of sportsbook vig. It uses the sportsbooks edge and the proportions of the odds to break the vig “responsibility” proportionately between the two odds. Let’s use the most common odds in sports -110/-110 as an example. We know that when we see these odds there is a 50% chance of the one side winning or the other. The first step in determining the fair odds implied probability:
Implied Probability = (-1*(Odds)) / (-1(Odds) + 100)
Or:
Implied Probability = (-1*(-110)) / (-1(-110) + 100)
or:
52.4% or 0.524 = 110 / 210

Since both sides of the bet offer -110 odds, we can double the Implied Probability to get 104.8% (1.048 as a decimal). The amount over 100% is the sportsbook’s vig or juice. We need to determine the proportion of the amount over 100% that each of the odds is “responsible” for. That means simply dividing them by the total percent of all odds:
Fair Odds = Implied Probability / Total Implied Probability of All Odds
or:
Fair Odds = 52.4% / 104.8%
or:
50% = 52.4% / 104.8%

Now we know the Fair Odds for -110 and can look for an edge if we believe the side we are looking at stands a better than 50% chance of winning. There are some strong warnings that come with this calculation: sometimes bookmakers play with the lines in a way that the sports bettor is always in the dark of. That means that they are considering the vig to be more the “responsibility” of one side of the bet or another. The Fair Odds model is the best guess as to what the sportsbook is thinking, though.

Looking for other calculators to use when sports betting? Check out:

Odds Converter

Futures Calculator

Parlay Calculator

Kelly Criterion Calculator

## When To Use A Fair Odds Calculator

The advantage of using a no vig calculator is clarifying the odds of winning. While a casino game will add rules that shift the odds in the house’s favor, a sportsbook will simply add a “vig” to the odds to make a profit. This addition can obscure the actual odds of the bet paying off.

If the sportsbook thinks you have a 50/50 chance of winning, they’ll list the bet as -110. The +100 would be the fair odds, and they take 1.01% from the potential payout as the vig. In American odds, the odds plus the vig translates to -110.

The No Vig Odds Calculator undoes that adjustment to help you better decide what bet is right for you.

Where things get really interesting is when you see the no vig calculator on odds that offer terrible payouts, such as -300. A \$100 bet would pay out just \$33.33, but the vig free calculator will show that the fair odds would be -143.18. Yikes.