How Odds Work in Sports Betting

Sports betting differs from playing casino games in several ways, but most significant is that it is far less dependent on chance. There is always some unpredictability of course, but with practice you will develop greater insight and can expect to reap the rewards.

A big part of that is understanding the different elements that go into betting on sports. Getting to know game rules and wagering options, before you put down any money is very important. The same can be said for odds, which is why we have explained the different types below.


Most of the betting odds that you’ll see online are not wholesale. They have been set by bookmakers, and adjusted to include a profit margin. This is also called an Overround, and is how sportsbooks make money and keep their businesses viable.

Wholesale odds, on the other hand, are what the pure probability is that an event will occur. Just a with wholesale goods, they are the price before profit has been added on by a vendor. Try to check these carefully to get a better idea of how likely a result actually is, whether you are working in Fractional, Decimal or American formats.


These are commonly seen, and use the following formula:

Probability (%) = B/(A+B)

For example, if you see Fractional Odds of 9/1, A is 9 and B is 1. The probability is:

                1/(9+1) = 1/10 = 10%

In other words, the chances of your sports betting prediction being correct are 10%.

Fractional Odds can also show you how much you will win if your bet is successful. Looking again at the A/B formula, for every value of B that you wager, you will get (A+B) back – your original punt plus your return. So if A is 9 and B is 1, for every 1 coin that you put down, you will get a return of (9+1), or 10 coins, if your prediction is right.


Decimal Odds can be derived from their fractional counterparts with this formula:

                DO = (A/B) +1

So, if we stick with A and B being 9 and 1, the Decimal version is:

                (9/1) + 1 = 10.0

That means that for every 1 coin you bet, your total return is 10. Your profit formula is (Odds x Stake) – Stake, so in this case:

                (10 x 1) – 1 = 9

A lot of people favour the Decimal option with sports betting, because you can see what your return is for every coin that you wager, without having to calculate it yourself. As you can imagine, this is a much easier situation when you are under pressure!


These are also known as Moneyline Odds, and are a popular option in the United States. The idea is to equalise the playing field between the favourite and the underdog. The team or player tipped to win is given a handicap, and a certain amount of points is deducted from their total. Their opponents, who are considered weaker, are given the same number of points as an advantage.

You’ll see the penalty and the advantage indicated by a + or – followed by a number, such as +/- 900. If the betting odds are totally even, no Moneyline symbol will be shown. If they are expressed fractionally as 9/1, you’ll see a +900 next to one of the teams, and a -900 next to the other.

You can also think of the positive number as how much you’ll be paid out if you bet 100 units and win. In this case, the negative value shows you how much you need to wagers successfully, in order to get a prize of 100 units. What should be clear from all the ways of expressing your chances in sports betting is that the higher the risk, the higher the potential return!

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