If you are just diving into the world of online sports betting, you’ve heard a lot about odds. These little numbers mean everything when it comes to sports betting. They tell you how to bet and how much you can make on your wager.

But how to calculate odds before placing your bet is no easy feat. It’s an art that takes time, practice, and patience to master. And the only way to begin strengthening your skills is by learning how it works.

If you’re ready to learn how to calculate odds and place the best wagers, we have all the formulas, equations, and simple explanations you need. Don’t place another wager until you know how to play online sports betting with our guide.

**Probability vs. Odds**

Before jumping into how to calculate odds, it’s important to address two of the most common terms: odds and probability. Some casual sports betting participants may accidentally use these words interchangeably, but there’s a clear distinction that you need to understand:

**Odds**are simply how frequently the desired result could occur. For example, in a coin flip where you call heads, there is one desired outcome out of two possible outcomes. This is a ratio of desired outcomes to possible outcomes.**Probability**is the likelihood that the desired event would occur. You divide the number of wanted results byte the possible outcomes. With the example of the coin flip, the heads side has a 50% probability.

Compare these to implied probability. Implied probability is the likelihood that an event will occur based on the odds.

**How Calculating Odds Works**

When you look at sports betting, you’ll see odds all over the place. Besides determining how much you’ll win based on the outcome, it also should inform your decisions.

Pros will calculate them based on specialized algorithms, formulas, and their knowledge of the topic. But you don’t need to be a professional in the gambling world or have a Ph.D. in math to use these numbers to your advantage — simply knowing how to calculate odds is all that matters.

Rather than a coin toss, let’s take something with more possible outcomes, like a spinning wheel. The wheel has six colors on it, and you want it to land on blue.

With six total colors, but only one desirable color, that means there are five undesirable outcomes. So a ratio for this would be expressed 1:5 — one chance you’ll win, five chances you won’t.

To calculate the odds of winning, or in favor, divide the desired outcome by the undesirable ones.

1 ÷ 5 = 0.1667

0.1667 × 100 = 16.67%

So based on these formulas, anyone who puts wagers down on blue has a 16.67% chance of winning. Compare this to an 83.3% chance of losing.

**Real vs. Implied Probability**

Now that we’ve covered how to calculate odds, let’s get back to probability. Because as we mentioned, these two terms are different concepts but often go hand in hand.

The odds will determine the implied probability. This is what you’ll find in sportsbooks. But with online sports betting, it’s important to remember the vig, also known as vigorish, juice, margin, or the house-edge.

Think of this as the house’s or bookie’s fee for taking on the wager. With the vig and other factors, the implied probability will vary from the real probability.

The real probability is simply the likelihood of the desired result. The true probability that you calculate may often differ from the implied probability. But that’s when you can determine whether you may have a good wager on your hands.

If you calculate a 55% chance of winning as reality, but the implied numbers are closer to 46%, this means you would have a good bet. Here are some tips:

- Look at the opening implied numbers in addition to current prices. They will have something to tell you about reality.
- Large discrepancies are a red flag (for example, 70% true chance vs. 25% implied).
- Reasonable discrepancies are a sign to go for it (for example, 55% vs. 50%). Take that bet!
- If the discrepancy is in favor of the sportsbook, best to let it go.

**How to Calculate Odds to Winnings**

With online sports betting, you have probably seen decimal numbers, ratios, fractions, and even pluses and minus signs. What does all of this mean, and what does it mean for your winnings?

With sports betting, there isn’t just one system. This means that the odds may sometimes look a little different. Understanding the similarities and differences between the main three systems is crucial not only to figure out odds but also your winnings.

Here is what you should know about each system.

**Fractional/British**

Fractional is most commonly used in the UK. It is also considered the best for sports betting with a large range of outcomes, like horse racing. When you’re looking at fractional numbers, the left number shows the likelihood that your bet would fail (according to the sportsbook) while the right is the likelihood of you winning.

The drawback is that it can be difficult to understand exactly what the likelihood of winning is and the risk involved. For example, comparing four-to-seven vs. three-to-eight may not seem like much of a difference without some math.

If you bet $40 for 9/2 odds, this is how it would turn out:

9 ÷ 2 = 4.5

$40 x 4.5 = 180

Calculating winnings is simple with the fractional system and provides the total payout. This is unlike the decimal system that we’ll be taking a look at.

**Decimal**

Decimal is the favorite of European online sports betting lines. The decimal is the amount that will be returned for each dollar you wager. This way, you can see both what you have staked and the winnings.

For example, you wager $10 at 2.5 odds. The total winnings are $25. Subtract $10 for the return of the risk, and you’ve profited $15.

**Moneyline/American **

The moneyline system looks completely different from decimals and fractions. With the moneyline system, you’ll typically see three numbers with either a plus or minus. The plus or minus show whether it’s positive or negative.

Positive means that the wager would be the underdog. There will be more money made if the outcome wins. Negative shows that this outcome is the favorite, making it more difficult to earn money from a wager.

When you see a positive, the number after is how much will be won for every $100 bet. So if you place $200 on +300 odds, you can use this formula to determine your winnings.

300 ÷ 100 = 3

$200 x 3 = $600

**How to Find Implied Probability**

With so many systems to work with, online sports betting may seem complicated. After all, how do you know when to bet based on fractions, decimals, and positives or negatives?

A far more simple way to understand the odds you’re dealing with is with percentages. We can all visualize probability out of 100. So to ensure you understand exactly what you’re risking, you can quickly turn all these numbers into percentages to see the implied probability.

**Fractional Odds**

Here, you’ll want to divide the number on the left by the number on the right. Divide two by this number. Then multiply by 100. So if the odds are 5/2, you’d do this:

5 ÷ 2 = 2.5

2 ÷ 2.5 = .8

.8 × 100 = 80% implied probability

**Decimal Odds**

This is the easiest system for finding the implied probability. Just divide one by the odds and multiply by 100. If the odds are two, you’d do this:

1 ÷ 2 = .5

.5 × 100 = 50% implied probability

**Moneyline Odds**

With moneyline bets, you have two scenarios: a positive and a negative.

The implied probability if you have a -200 moneyline bet:

(-(-200) ÷ ((-(-200)) + 100 =

200 ÷ 200 + 100 = 200 ÷ 300 = .6667

.6667 × 100 = 66.67% implied probability

Now let’s say you take the underdog at +250:

- 100 ÷ (250 + 100) =
- 100 ÷ 350 = 0.2857
- 0.2857 × 100 = 28.57% implied probability

**Find the Best Odds**

Now that you know everything there is to know about how to calculate the odds, it’s time to have some fun and win some money. Make sure you use all the knowledge you have about odds and probability to get the best results for your sports betting – and be patient. This is really technical stuff, and you won’t master how to calculate odds in a day.

Whenever you’re ready to place your bets, head over to our favorite online sports betting partners — you will get the most favorable odds out in sports betting!