When you log into an online sportsbook, you can choose from a ton of different offerings. They can include straight bets – moneylines, spreads, and totals – but there are a host of other options available as well. Team futures, player prop bets, and specials are also available for basically every sport that the sportsbooks offer.

Of course, not all of these offerings are priced the same way. After all, it wouldn’t be particularly fair if the Chiefs were priced the same as the Texans to win the Super Bowl.

That’s where betting odds come in. The betting sites assign a number to each wager – also known as the vig or juice – that determines the potential payout. The less likely an event is to happen, the greater the theoretical payout should be if it does occur.

Odds calculation comes into play here. If you’re able to determine the likelihood of an outcome vs. the probability that the oddsmakers have assigned to it, you can search for value all across the sportsbook.

We have a fantastic Betting Odds Calculator available for free at Fantasy Life, and it can be an extremely valuable tool for bettors. Let’s dive into everything you need to know to get the most out of this tool.

Why Do Betting Odds Matter?

Betting odds help us identify good bets and bad bets within the marketplace. Let’s look at the Super Bowl futures market as an example. 

You might think the Chiefs are the most likely team to win the upcoming Super Bowl, and they’re priced that way at DraftKings Sportsbook. They’re followed closely by the Eagles and Bills before giving way to some of the longer shots:

DK Odds

Since the Chiefs are listed at +600, it essentially means they need to have a better than 1/7 chance for the bet to have value. The Eagles would need a better than 1/7.5 chance, while the Bills better than 1/10. Anything worse and the “true odds” would be less than the listed odds, making them a bad investment.

This can be easily identified using our Odds Calculator Tool. Entering the +600 American odds spits out fractional odds of 6/1, decimal odds of 7.0, and an implied probability of 14.3%.

The last number is the most important. Do you think the Chiefs have a better than 14.3% chance of winning the Super Bowl? If so, then +600 is a good number.

This is also true for straight bets. Most point spreads and totals are priced at -110, which translates to an implied probability of 52.4%. That means that 52.4% is your break-even point for those wagers. If you’re hitting more than 52.4% of your -110 wagers, you’re going to be in the black. If you’re hitting less than that frequency, you’re going to be in the red.

Moneyline odds work similarly. Bets placed at +100 have exactly a 50% break-even mark. Moving up to -150, the break-even point moves to 60%. The shorter the odds, the higher your confidence level needs to be in order for it to be considered a profitable wager.

How to Use the Odds Calculator Tool

Like most of our betting tools, using our Odds Calculator Tool is incredibly simple. All you need to know is how any particular bet is listed in one format. That can be American odds, fractional odds, or decimal odds. If you’re looking for more information about those formats, check out this primer I did on how to read sports betting odds.

Once you have your preferred odds, you can put it into the calculator to get all the additional information.

Let’s go back to the -110 example. This is the industry standard for spread bets and totals, particularly when it comes to NFL betting, so it’s one that you’re going to see a lot. Putting -110 into the calculator will give you the decimal odds, fractional odds, and implied probability:

Betting Calculator

There’s also a space where you can input your bet amount. This is also known as your “stake.”

If you want to win $100, the correct stake in this instance would be $110. That said, if you’re uncertain, you can use that field just to confirm that your wager is resulting in the desired payout.

The “to win” section shows only the potential profit for your wager, while the “payout” section includes your initial stake.

Betting Odds Calculator

What Kind of Bets Do Odds Converters Apply To?

As mentioned previously, odds converters are a useful tool for virtually any bet in the sportsbook. Knowing the implied probability of your wager – aka the break-even point – is vital information for sports bettors. This is true for basically every sport, including the NFL, NBA, MLB, NHL, and even horse racing.

These can include (but are not limited to) the following bet types:

  • Moneylines
  • Spreads
  • Totals
  • Player Props
  • Team Props
  • Specials
  • Futures

I find odds converters to be particularly useful when it comes to long shots in the futures market. For example, what is really the difference between +4000 and +5000? It’s obviously an extra +1000, but how much less likely is that bet to hit?

Using the odds calculator, +4000 translates to an implied probability of 2.44%, while +5000 translates to 1.96%. That’s almost nothing!

Going back to the Super Bowl odds, the Browns, Saints, and Broncos are all listed at +4000, while the Bears and Steelers are listed at +5000. We’re obviously talking about long shots with all five of those teams, but do the first three feel that much stronger than the second two? We’re talking about an extra +1000 – in other words, an extra $1,000 on a $100 wager – for less than half a percentage point in implied probability. That doesn’t necessarily mean the Bears and Steelers are better bets, but it does mean that the gap between them and the other squads is narrower than you might think.

Using an Odds Converter to Hedge

This is another extremely useful spot to consider using Fantasy Life’s Odds Calculator Tool. Hedging is something that you should strongly consider, particularly when it comes to longshot futures. When done properly, it can be done to help grow your bankroll in a responsible manner.

Let’s say that you did take the Bears to win the Super Bowl at +5000 from the previous example, and they made it all the way to the NFC Championship game. They’re now facing the Eagles, who are listed as -250 favorites.

That Bears’ ticket now has immense value, but you don’t want to risk winning nothing if they lose to the Eagles. Let’s say your initial bet was for $100, meaning that you risked $100 to potentially win $5,000. How much do you have to bet on the Eagles to ensure that you’re going to walk away a winner in both possible outcomes?

Let’s say you want to win $500 if the Eagles win this contest. Using the odds converter, you could input the -250 odds to find your desired bet size of $1,250:

Now, if the Eagles win, you’ll put $500 in your pocket. That covers your initial investment on the Bears plus an additional $400. If the Bears win, you still have your 50-1 ticket on them to win the Super Bowl. That opens up another hedge opportunity in their last contest, but the effective value of that ticket is still +3750 ($5,000 minus the $1,250 wagered on the Eagles). That still leaves plenty of room for an additional wager on their opponent without sacrificing all of your potential profit.

American vs. Decimal vs. Fractional Odds

Essentially, these are just three different ways of looking at the exact same thing. For American odds, everything is based on a hypothetical $100 wager. Anything with “minus odds” is considered a favorite, and you need to risk that much in order to win $100. That means on a -120 bet, you’d have to wager $120 to profit $100.

Fractional odds work similarly to American odds; they just don’t assume a $100 wager. If you take your desired stake and multiply it by the listed fraction, that will show you the potential payout.

We already know that -110 American odds convert to a 10/11 in fractional. If we take our $110 wager and multiply it by 10/11, we get $100. Any number that is greater than one (i.e., the numerator is larger than the denominator) is considered a bet on an underdog. Any fraction with a value of less than one is a bet on an underdog.

Decimal odds work similarly to fractional, but they include your original wager in the calculation. If you take your initial stake and multiply it by the decimal odds, the result includes the total payout. That includes the potential profit and your original wager.

The -110 American odds translate to roughly 1.91 in decimal odds. Multiplying $110 by 1.91 gets you to $210; your original wager, plus $100 in potential profit.

Note that decimal odds can never get lower than 1.00 since that represents your initial stake. Anything above 2.00 translates to a better than even-money wager in American odds, while anything between 1.00 and 2.00 represents a bet of even money or worse.

You can typically change your preferred online bookmaker — Caesars, FanDuel, BetMGM, BetRivers, and more — to use whichever odds format you prefer.

Common Conversions

American Odds

Fractional Odds

Decimal Odds

Implied Probability