OnlineSportsBetting
By , Updated on: Sep 12, 2025 12:00 AM

All sports bettors can benefit from using odds calculators—especially if they’re placing wagers across different markets where currencies vary and odds are presented in multiple formats.

These tools are also useful if you’re looking to calculate returns on parlay betting and arbitrage wagers. However, their main function is to explain and convert different types of betting odds so you don’t get confused when investing in certain lines.

Don’t worry if you’ve never used this little helper. We’ll run you through everything you need to use our calculator if you continue scrolling.

Our betting guide contains several pages in order to make you understand the betting world.

Betting Odds Calculator

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American Style (eg. +110, -200)
European Style (eg. 3.24)
Traditional Style (eg. 6/1)
Percentage (eg. 45%)
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Different Types of Odds

American Odds

These are the most common forms of betting lines. Pretty much every online sportsbook prefers to roll with the American odds format. Even if they don't, their servers can often detect your location, and if you're in a territory that predominantly uses American odds, this will be how all the event lines you see are presented.

Reading American odds is fairly straightforward. They are written as either negative numbers (for example, -110 or -250) or positive numbers (such as +150 or +250). Negative odds tell you how much you need to risk in order to win $100. So, if the line is -250, you would need to wager $250 to make a profit of $100, in addition to getting your stake back. Positive odds, on the other hand, show how much profit you stand to make on a $100 bet. For instance, a line of +250 means that a $100 wager would return $250 in profit, plus your original $100 stake.

On the flip side, let's say you're dealing with a +250 moneyline. For positive odds, you're simply seeing the amount of money you stand to win for every $100 you bet. In this instance, each successful $100 wager will result in a $250 profit.

For those who prefer other odds formats, you may need to convert American odds to decimal to compare lines across different sportsbooks. Using an American to decimal conversion, a -250 line translates to 1.40 in decimal format, while a +250 line would be 3.50. Many betting platforms offer a built-in spread to moneyline converter or spread to moneyline calculator to help bettors transition between different odds types.

Decimal Odds

Decimal odds are also incredibly easy to interpret once you get the hang of them. As the name suggests, they're presented in a decimal format: 1.00, 1.50, 2.75, etc. These odds represent the amount for every $1 wagered.

So, if you're placing a bet on an event with decimal odds of 2.50, you're looking at a payout of $250 for every $100 you invest—or a profit of $150 total. If you're used to American odds, you can quickly convert using the decimal odds to American formula to get a clearer picture of potential winnings.

Odds Calculator Vector

Fractional Odds

Fractional odds are easy to identify, though not as simple to calculate. These are all presented with slashes, such as 3/2, 5/2, 1/1, and all that. When odds are written in this format, they tell you how much cash you can win on your bet in comparison to your stake. It can seem a little confusing at first, but with a bit of practice fractional odds are easy to understand. The number on the left shows how much you can win, while the number on the right shows the amount you need to stake. For example, with 5/4 fractional odds, you would win $125 in profit for every $100 wagered. That means a $100 bet would return a total of $225—your original stake plus $125 in winnings.

Implied Odds

Many sports bettors won't come by implied odds too often. These lines are essentially traditional American odds converted into percentages. And while many of the other line types can be calculated manually without much issue, these are more complicated. Implied odds do not account for the "juice". In other words, investing in a +100 line, which has a 50 percent implied probability, doesn't mean you'll successfully hit 50 percent of the time. It instead means you would need to win half your bets to break even.

Why Use a Betting Odds Calculator?

Betting Odds Conversion

The absolute best part of a betting odds calculator is its conversion. It takes whatever odds you input and then relays them in all the most common forms. Just for kicks, let’s suppose you’re looking at the latest NFL futures odds and decide to take the Buffalo Bills at +600 to win Super Bowl LX (the upcoming Super Bowl in early 2026). If you plug this into a betting odds calculator, you’ll get a return along the lines of the following:

American Odds: +600
Decimal Odds: 7.00
Fractional Odds: 6/1
Implied Probability: ~14.29%

This is super useful if you're someone who, in this case, is used to fraction odds but looking at a sportsbook that only provides lines using American odds. Rather than having to figure it out in your head—which, are you really figured out 23/4 in your head?!?—the proper presentation is right there in front of your face. But the benefits to betting odds calculators don't stop there...

Betslip Breakdown

Any betting-odds calculator worth its salt will not only convert different lines, but it will tell you how much you stand to win based on how much you wager. Time for another hypothetical. Let’s say you’re checking the latest NBA futures and see a team listed at +750 to win the championship. You want to wager $500, but the odds are only shown in American format and you’re more comfortable with decimal or implied odds. That’s when you can plug the information into a betting odds calculator, which will instantly convert the line and show you your potential return.
  • American Odds: +750
  • Decimal Odds: 8.50
  • Fraction Odds: 15/2
  • Implied Odds: 11.76 percent
  • Bet Amount: $500
  • To Win: $750
Just like that, you don't even really need the converted lines—though you'll still have them. You'll instead know that a $500 bet on the Lakers to win the title could net you $3,750 in profit. The easiest to use betting calculators will even sum up the total potential winnings for you—the initial investment plus whatever profit you stand to gain. In this example, your entire return would be $4,250: The $500 you put down on top of the $3,750 you stand to win.

Betting Calculators and Parlays

Sometimes, people don't need betting calculators and odds converters. They don't plan on placing wagers in different markets and don't have to worry about coming across decimal or implied odds when they traffic exclusively in American lines. However, if you do find yourself needing to convert American odds to decimal, especially when comparing sportsbooks with different formats, a simple conversion tool can come in handy.

That's all well and good. You may never need to use an odds converter when submitting single-event wagers. You can easily calculate the risk and reward or just know it by memory, since so many sports use repetitive odds when it comes to games or futures outcomes.

What about when you want to place a parlay bet, though? Well, this changes everything. You may need a parlay odds calculator. The tool on our page allows you to select an odds type and build out mock parlays before spitting out everything you need to know about how much you'll win based on how much you'll bet.

Odds Calculator Vector For our purposes, let's say you're shopping around the latest MLB odds and want to parlay the winners of all six divisions. Your theoretical budget is $100, and in this hypothetical situation you're taking the following teams and their American odds price points: New York Yankees (+150), Chicago White Sox (+225), Houston Astros (+125), Miami Marlins (+300), St. Louis Cardinals (+100) and Los Angeles Dodgers (-150). Calculating your return based on a $100 investment is impossible on your own. If you plug all the individual lines into a parlay betting odds calculator, though, you'll receive some variation of the following instantly:
  • Bet Amount: $100
  • To Win: $24,275.00
  • Total Payout: $24,275.00
See how easy that was? It saves you a ton of time. And while many online sportsbooks have these calculators on your bet slip, this is a great way of discerning payouts if you don't want to built or ticket or simply haven't registered with a bookie just yet. Favorite this page and come back to us whenever you need an odds calculator!