Why Do Sports Betting Sites Have Different Odds?

Predicting the probability of a specific outcome of any event or sport isn’t an exact science. Although most of the calculations are based on facts and statistics, the interpretation of the information is still, essentially, a matter of opinion.

Sports betting is a game of chance. A bookie can have an excellent analytics team or software program, but there will always be a random element that we can’t exactly quantify. It all comes down to this: no sports betting site can definitively and accurately predict the likeliness of an outcome.

Before we continue, please remember that no method can give you a 100% accurate prediction of an outcome. Always remember to gamble responsibly.

We’re going to be taking an in-depth look at:


What Are Sports Betting Odds?

Odds by the sports betting sites

To get a proper understanding of sports betting, you first need to understand what odds are. You must also know how to tell some bookmakers by odds from another.To make it a bit easier to understand, we’re going to look at a simple example using a fictional tennis match between Djokovic and Gasquet.

Djokovic is the top-ranked player, and he’s going up against Gasquet, ranked at number 50. Logically, Djokovic is going to be the favourite to win over Gasquet. Not only is there a massive gap in their rankings and ATP points, but Djokovic has won 79 ATP titles, 17 Grand Slam titles and a lot more besides. Gasquet, despite an impressive track record, has only won 15 ATP titles. He makes the final several times, but rarely takes home the gold.

Obviously, the chance of Djokovic taking Gasquet to the cleaners is exceptionally high. That makes Djokovic the favourite, and Gasquet, the underdog. What does that mean for the odds? Gasquet, being the underdog and less likely to win, is going to have the odds stacked against him. Djokovic, however, will have much lower odds since he’s the favourite. Betting on Djokovic would be the safe choice, but you’re probably not going to see a noticeably big pay-out if he wins. Gasquet is the riskier wager, but if he does win, you’ll be adding a pretty penny to your pocket.

Basically, odds are probabilities. It’s saying, ‘the probability of this outcome is more likely than that outcome’. It might be a simple explanation, but it does give you the general idea of the role they play in sports betting.

Betting Odds Formats

Odds can be expressed in different ways, some of which are easier to understand than others. These formats are:

  • Moneyline
  • Decimal
  • Factional

The chances that you’ll encounter one or all these formats are quite high. For that reason, being familiar with each one will pay off in the long run. The three formats primarily work in the same way and are merely different ways of expressing the odds for any particular bet.

Moneyline or American

Moneylines are frequently referred to as American odds, and it’s the format used by most betting sites in the United States. They can be displayed as a positive or negative number. A positive number shows you how much a correct wager of, say, £/€/$100 could win, whereas a negative number indicates how much you’d need to stake to win £/€/$100.


Decimal odds are most frequently used in Canada, Australia and a large part of Europe. That said, it’s quickly becoming a standard format with most bookmakers globally, except for US bookies.

Decimals are probably the most straightforward of the different formats, expressed in a single positive number with up to two decimal places. It’s also relatively easy to understand, and we can show that with a remarkably simple example:

Let’s say you’re placing a bet of £/€/$1 at 1.5 odds. That means you’ll get £1.50 if you win your wager. On a larger scale, that would mean a return of £/€/$1.50 for every £/€/$1 you wager, so a winning bet of £/€/$100 at 1.5 will give you a total win of £/€/$150.

Simple, right?


We expect that you’ll likely already be familiar with fractional odds. This format is most popular in the United Kingdom, even though decimals are slowly starting to take over.

Calculating your potential profits with this format can be a little tricky, especially if you’re still a beginner. On the surface, it may seem simple. With odds of 5/1 or five to one, you can win back £/€/$5 for every £/€/$1 you wager. Evens, or 1/1, will give you a pound for a pound.

Unfortunately, fractions can get a lot more complicated. Take 6/4, or six to four. You can win £6 for every £4 wager – that’s the same as the 1.5 odds listed in our decimal example. The fractional format certainly isn’t the most popular or even the most accessible format. Still, even with the growing popularity of the decimal format, we doubt that the fractional format will ever disappear completely.

How Do Bookmakers Calculate Betting Odds?

If you’re a frequent bettor, you should be aware by now that not all bookmakers have the same view on how to interpret and analyse information. They also don’t use the same systems to convert their results into odds.

Many different variables affect how professional bookmakers determine their odds, and not all these bookies interpret information in the same way. Public opinion, competition, historical statistics, favourites and profit can all affect how one bookie sets its odds compared to another.

The amount of information available also plays a significant role. The more information the bookmaker has, the better the chance that it will have of estimating accurate odds. However, if it doesn’t have enough information to make a semi-accurate prediction, then a bookie will err towards caution, and set the odds in its own favour.

Let’s take a closer look at four factors that can have an impact on how a sportsbook determines its odds:

Current and Historical Information
Profit and Balancing the Books
Internal and External Teams – The Human Factor

Getting the Best Odds – Our Top Tips

Tips for best odds

Below we have outlined our tips to help punters find the best odds online. Read them through and come up with betting strategies to help you come out victorious after your wagering sessions. Bear in mind that these are just a few of the things you can do for odds monitoring and finding true value bets.

1. Shop around

Much like retail prices can vary from one store to another, some bookmakers will have better wagering opportunities than its competitors. Even though the differences might be small, they can still have a significant impact, especially on your bottom line. The more you wager, the more significant the impact of that small variance will be.

We highly recommend that bettors do “line shopping” and compare odds before placing any wagers. Whether you’re punting just for fun, or you’re set on becoming a serious bettor, this strategy should always serve you well.

2. Calculate your own odds

This is a tricky one, but it’s one of the skills that you can develop that will probably pay off the most. Calculating an exact and accurate probability of an outcome is impossible, and being able to come up with your own odds won’t suddenly give you a super ability to beat a bookie consistently. If it did, then we’d likely all have given up our day jobs to become millionaires.

Whether you’re an experienced punter or not, you should still have a basic ability to calculate odds – it’s something we all do every day. Are you going to take a new job offer? If you speed through the yellow light, are you going to make it to the other side safely?

We all need to make rational and objective decisions and mitigate the risks of everyday life. Those same principles are what skilled bettors use to determine whether to place a bet or not. With time and practice, and a lot of research, you can calculate your own odds and compare them to those of bookies to spot good deals.

3. Exchange betting

Many professional bettors exclusively bet on exchanges. Exchanges are platforms, such as Betfair, where anyone can lay or back a bet. Conversely, a bookmaker is the one putting up money as lay bets against punters’ back bets, an exchange allows players to place lay and back bets against each other, taking a small portion of all winnings as commission.

In a way, this allows players to ‘control’ the odds through their wagers. The result is that exchanges often have significantly better odds available than bookmakers do.


To stand any real chance of placing winning wagers in sports betting, you first need to understand what odds are and be able to calculate your own. It’s a fundamental skill that any punter should have. Why? Because it makes it easier to spot discrepancies in a bookie’s listings, giving you the upper hand.

Odds are an integral part of sports betting; it’s the foundation on which this exciting hobby was built. That said, it’s probably one of the hardest things to understand, and it often confuses and stumps new punters. Having different odds across sportsbooks can just add to that confusion. However, when combining them with the some bonus code offers you will be able to make the most of your stay on a betting site.

Knowing about all the different variables that go into calculating the numbers, and how different bookies factor these variables into their own analyses, should give you a better chance of placing a winning wager in the future.

Remember, bookies will rarely offer the same odds, and you can make those discrepancies work for you. Shop around before placing a wager, look for value bets and do your research. Good luck, and may the odds be ever in your favour!

Expert Найден Панайотов
Найден Панайотов
Nayden is the content manager of Efirbet.com! He is one of the main reviewers of all articles you will see on the site.