Implied Probability Calculator

Gaming Today’s Implied Probability Calculator will take the math out of your hands and help you determine the likelihood of an event occurring based on the betting odds. This calculator can be used for any bet, from moneylines and point spreads to player props and futures.

Use the Implied Probability Calculator to convert any American odds into implied probability (the likelihood of the event occurring). The result will be displayed as a percentage you can compare with your probability assessment. A betting opportunity is available if you think a team has a 55% chance of winning a game and the sportsbook’s implied probability is lower.

How to Use the Implied Probability Calculator

First, enter the American odds and click “Calculate” to get the implied probability of the event occurring.

For minus odds (regularly listed for betting favorites), you must place the minus symbol (-) before the odds to get the correct percentage.

If the implied probability for your selected bet is lower than your assessment, then the odds are in your favor, and an educated wager can be placed.

The implied probability is the percent likelihood of the event occurring whereas the true probability would remove the sportsbook’s vigorish (or “vig”) — also known as the commission placed on a betting market. This Implied Probability Calculator includes the sportsbook’s margin, which means the combined probabilities won’t add up to exactly 100%.

Implied Probability Calculation: NFL Example

Let’s look at how the Implied Probability Calculator works for an example featuring NFL moneyline odds and North Carolina sports betting.

The Dallas Cowboys are listed at -400 against the Carolina Panthers (+310). At -400, the Cowboys have an 80% implied probability of winning the game. Meanwhile, according to the sportsbook’s betting line, the Panthers have a 24.39% shot at victory.

Observant bettors seek value in moneyline bets, and it’s important to convert the odds into implied probability. If you think the Panthers have better than a 24.39% chance of winning the game, then there’s value present in their +310 odds.

How the Implied Probability Calculator Works

Gaming Today’s Implied Probability Calculator converts betting odds into implied probability (or the likelihood of an event occurring).

Implied probability is most useful when determining the sportsbook’s edge over the bettor. It’s important to note that this is not the margin/vig/juice. This is simply the advantage they have in being profitable over the bettor.

Though it will never tell you which team to select, determining the percent implied probability over 100% will point out lines where the book’s advantage is lower. In being a successful sports bettor, every percentage point counts, and each point the book gives back is one more win toward profitability for the bettor.

Calculating Implied Probability for Negative American Odds

Calculating implied probability is a little more complex with American odds. Let’s take the classic coin flip example where we know the actual probability is 50%: a -110 bet on Heads. The calculation is slightly different for minus odds versus plus odds:

Implied Probability = (-1*(Odds)) / (-1(Odds) + 100)

Which looks like:

Implied Probability = (-1*(-110)) / (-1(-110) + 100)


52.4% or 0.524 = 110 / 210

That number should be familiar to experienced bettors as the break-even winning percentage bettors shoot for. Because -110 on one side of a bet usually means -110 on the other side, too, we can add all the probabilities (in this case, another -110 probability) to determine the sportsbook’s edge.

(Heads Probability + Tails Probability) – 1 = Sportsbook’s Edge


(0.524 + 0.524) – 1 = 0.048 or 4.8%

Ideally, you should be looking for bets with the lowest sportsbook edge you can. It is a subtle edge in sports betting, but remember, the difference between winning at 52% and 53% is a world of difference.

Calculating Implied Probability for Positive American Odds

Now, let’s take a look at an example featuring positive odds. We’ll use the following moneyline bet where the favorite is listed at -190 while the underdog is +160. First, we break down the implied probability on +160 odds:

Implied Probability = 100 / (Odds + 100)


38.4% or 0.384 = 100 / (160 + 100)

To get the other outcome, we calculate the -190 odds:

65.5% or 0.655 = (-1(-190)) / (-1(-190) + 100)

In the above example, we see that the sportsbook’s advantage is:

(0.384 + 0.655) – 1 = 3.9%

This tells us that, with no other information, a bet on the -190/+160 is more likely to be successful over the long term than the -110/-110 example.

Sports Betting Tools

If you’re looking to crunch the numbers for any bet, we have you covered with the following sports betting calculators:

No-Vig Calculator | Futures Calculator | Moneyline Calculator | Parlay Calculator | Martingale Calculator | Kelly Criterion Calculator | NFL Point Spread Calculator | NFL Prop Bet Calculator | Odds Calculator | Sports Betting ROI Calculator

Implied Probability Calculator FAQ

When should I use an Implied Probability Calculator?

You should use an Implied Probability Calculator anytime you want to place a bet (moneylines, point spreads, totals, futures, props, etc.). Use the calculator to determine the percent likelihood of each outcome occurring, compare your own probability assessments with the sportsbook’s, and identify odds that may be mispriced.

Is it legal to use an Implied Probability Calculator?

Yes, it’s legal to use an Implied Probability Calculator to help form strategic betting decisions. Sharp bettors use sports betting calculators to research available betting markets and gain an edge over the sportsbooks.

Who sets the odds at online sportsbooks?

Sportsbooks employ bookmakers who are tasked with setting the odds for each game and futures market. After setting a betting line, the sportsbook will shift the odds one way or the other depending on public betting, player injuries, and several other factors.

How do you calculate implied probability?

With decimal odds, you can determine the implied probability by dividing them by 1 and multiplying the result by 100: 1/odds x 100. For example, if the odds are 3.0, the implied probability is: 1/3.0 x 100 = 33.33%.

How do I convert American odds to fractional odds?

To convert plus (+) American odds into fractional odds, you must divide the odds by 100 and convert them to a fraction. To convert +160 into fractional odds, for instance, divide 160 by 100 (160/100) and reduce that fraction to 8/5. American odds of +160 translates to 8/5 fractional odds.

To convert minus (-) American odds, divide 100 by the odds and convert them to a fraction. For example, with -160 odds, calculate as 100/160, and reduce to 5/8 fractional odds.

About the Author
Brian Spaen

Brian Spaen

News Managing Editor
Brian Spaen is the news managing editor of Gaming Today. He has been a content writer and editor in various industries, including sports betting, environmental technology, and higher education. Brian is a graduate of Iowa State University and currently resides in Des Moines, Iowa.

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