The gambling industry is built on different types of betting odds, all of which will tell you how valuable a certain bet is and whether it’s preferable to another. If you’re looking to place a bet then it’s important that you learn these different types of betting odds. In this article, we’ll help you to do just that, looking at sports betting odds and online casino odds to prepare you for your next online gambling session.

Best Online Sports Betting Sites & Sportsbooks in the USA

What are Betting Odds?

In simple terms, betting odds are used by gambling sites to tell you how valuable a bet is and how much money it will return if it wins. These odds are based on probability for the most part, but it would be incorrect to assume that this is the only factor at play.

After all, if you were betting on the flip of a coin, you know that you have a 50% chance of hitting either Tails or Heads. If you were betting on a match contested between two fierce and closely matched rivals you might expect the same probability. But the only way a bookmaker would profit from this is if more people bet on Team A and Team B won. But bookmakers don’t gamble—they run a business and a business needs to be built on some consistency and certainty.

To counteract this, they reduce their odds and then pocket the difference. This means that while the probability of the outcome matches 50/50, the actual odds are closer to 45/45.

Different Types of Betting Odds

There are several different betting systems used on sports books. These systems are popular in different regions and are used for different purposes. If you’re going to learn just one system, it’s best to stick with decimal, as it’s by far the most popular and also allows for the greatest variety. However, if you’re going to be placing a variety of bets on a number of websites, it will benefit you to learn all these systems.

Fortunately, they are all very simple and require the briefest of explanations, as discussed below :

Fractional Odds

Most common in UK and Ireland, these odds are most commonly seen in horse and greyhound racing but can also be found on a host of British-based sportsbook. They are often displayed as a simple fraction, such as 2/1 or 3/1.

There is one easy trick you can use to remember how these odds work: Just imagine that the second number is your stake and the first your profit. If you add them both together, that will be your total return if the bet succeeds.

For instance, if you bet €10 on odds of 2/1, you will win €20 and get your €10 back for a total of €30. These odds can also be expressed as “Evens”, which is the same as 1/1, or as “Odds-On” which is reserved for the short-priced favourites and looks like this: 1/4. In this case, you can use the same tactic to predict your return. A €10 bet would return a profit of €2.50 (because €2.50 is ¼ of €10) for a total return of €12.50.

Decimal Odds

The decimal odds system is commonly used in Europe and Asia and is found on most, if not all online betting sites. Even the ones that are not based in Europe or Asia still offer this system following a simple conversion.

Decimal odds are often displayed as several digits and a decimal point, such as 3.00, 4.56 or 150.00. Many players familiar with fractional odds will simply convert decimal into fractional by reducing the first digit by one, but while they may seem confusing to the uninitiated, decimal odds are actually much more straightforward.

To calculate decimal odds, simply imagine the number as your total return from a €1 bet. For instance, odds of 3.00 would trigger a total return of €3 (€1 stake; €2 win) while odds of 150.00 would return €150 (€1 stake; €149 win). The great thing about decimal odds, when compared to the fractional system, is that they allow for more incremental odds changes and are easier to understand once those small changes take place.

For instance, everyone can guess what 5/1 or 6/1 means, just as they know that 6.00 and 7.00 mean the same thing. But while 5.60 is just as easy to calculate (a €5.60 return for a bet of €1) the same can’t be said for 23/5. It’s easy to predict a return from €5, but what if you want to bet €1, are terrible at mathematics and don’t have a calculator on hand?

American Odds

The American betting system, also known as Las Vegas or Moneyline odds, is common in the United States, but rarely used outside of the country. These odds are most common in Las Vegas, where bettors use them to place bets on American Football, Baseball, and Basketball.

American odds are suited to these bets and this environment because they work best when there are only two outcomes and bettors are staking big money.

Here is an example of a game with American odds:

  • Team A +330
  • Team B -250

To understand these odds, just remember that the Plus estimates how much you can win with a €100 bet, while the Minus estimates how much you need to stake to win €100.

So, a €100 bet on Team A would net you €330 while you’d need to bet €250 on Team B just to win €100. In both cases, you will also get your stake returned.

Sports Odds Explained

All the above betting systems are used on sports betting sites. Decimal is by far the most common thanks to its widespread use in Asia and Europe and its adoption by the world’s biggest betting exchanges.

Fractional odds are common on many big-named UK and Irish sportsbooks. American odds are less common online as gambling has been tightly restricted in the US over the last few years and while that has been steadily changing, many legal sites have adopted the decimal system.

Other Types of Betting Odds

We have discussed the types of sports betting odds above, but what about online casino odds? Well, for one thing, online casino games work a little differently. There are no odds as such, but there are a few different things that differentiate these games from one another and allow you to determine whether one game gives you more chance of winning than another.

These are as follows:

House Edge

A house edge is defined as the advantage that a casino has over you. The lower this is, the lower their edge is and the greater your chance of winning will be. A house edge is often used for table games and is at its lowest for card games like Blackjack and French Roulette.

As an example, a Classic Blackjack variant, which is played with a single deck of cards, typically has a House Edge of less than 1%. This means that if you were to bet $1 a game and play 100 games, then the casino would expect to win a $1 profit.

Of course, it doesn’t quite work out that way. The casino may win a lot more or you may win money from them. This is just the average and it’s an average calculated over millions of hands across many thousands of users.

Some games will increase this edge by adding things that are more favourable to the casino. Such is the case with games of Spanish 21, which was created more or less specifically for this purpose. Casinos will also add more decks to the shoe to increase the House Edge.

Roulette is another good example. In games of French Roulette, the House Edge for most bets is 2.70%. However, the additional Green Zero space added to games of American Roulette increases this edge to 5.26%.

Different bets also return different House Edges. As an example, if you bet on the Banker’s hand in a game of Punto Banco Baccarat then you can expect a House Edge of 1.06%, which is very low. It’s a similar story with the Player bet, albeit slightly higher. However, if you stake your money on the Tie, then you can expect a House Edge greater than 14%.

Return to Player (RTP)

The Return to Player average, or “RTP”, is very similar to a House Edge, but it works in the opposite way and is commonly found on slot machines and not table games. Many slots have RTP’s higher than 95%, which means that if you bet $100 then you can expect a return of $95. Again, however, this is just an average and it doesn’t mean that you will get exactly this amount.

The best developers, including NetEnt, make it their mission to create slots with RTPs of no less than 94%, but there are some games out there that offer sub-90% RTPs, which is definitely not favourable and should be avoided if you’re looking for big and consistent returns.


The volatility level is often overlooked but it can help you to decide if a specific slot machine is right for you. Also known as variance, this dictates how often a game will pay out and how much those payouts will be.

A low volatility slot will pay out regularly, but the wins will generally be very small; a high volatility slot will pay out much less frequently, but the wins tend to be much bigger. This is an important factor to consider, because if you’re planning a short session with a limited budget, you’re much more likely to lose all your money if you opt for a game that has high volatility.