How to convert betting odds

Betting odds are, to the uninitiated rather…odd. They come in a number of different guises and can take a long time to get your head around which, unsurprisingly, is not unusual when it comes to a number-crunching business.

Finding the best value requires a good knowledge of both the sports in question and the odds available so being able to understand what the odds actually mean is of vital importance. This is why being able to convert betting odds will be a huge help to those interested in having a flutter.

We have, therefore, putting together a bit of a guide to help you understand what odds are, how they work and how to convert them from one standard to another.

We hope you find this helpful. Read on to find out more:

What are betting odds?

Starting with the fundamentals let’s take a look at what odds actually are. The easiest way to explain it is by saying they are a number representation of how likely an event is to take place. In betting it is slightly different as the odds are a representation of payoff to stake i.e. they tell you how much you will receive as a return if the bet you place comes off.

To give an example, if Manchester City are playing Southampton and you bet on Man City to win then you are likely to get odds of 1/2 (these are just examples as actual odds may vary. This implies that Manchester City are likely to win the game twice as often as they are to lose it (if it was 1/1 then you’d expect them to win five out of 10 matches or half and half). This means that every pound you staked will see you receive 50p as a return so if your stake was £10 your winnings will be £15 (£5 profit). If an event is likely to happen one time in every six attempts then the odds of probability are 5/1 and in a bet of this type, the player would receive £50 for every £10 they stake.

Odds are linked to the probability of the event in question so if you take the throwing of a die as an example you know that it has six sides each with a different number on it from one to six. This means that the probability of throwing a four is 5/1 as every one time you get four you’d expect another five times to get one of the other numbers.

Betting companies make their money by having odds that are slightly in their favour and do not often link exactly to probability but they are very much linked.

The different type of odds

There are two main types of odds which are both displayed in different ways. They are known simply as fractional odds and decimal odds and by their name you can probably tell they are just different numerical ways of showing the same thing.

Converting betting odds is an important skill to master to make sure you are always betting with your desired price, as some bookies might only show one of the two options

• So in fractional odds, as a gambler, you work out how much you’d get from a 4/1 event that you have put £10 on by multiplying the right number by the left (10 x 4) which gives you a £40 profit plus the return of your stake so £50 in total. It tells you how much you stand to earn in relation to your stake.

• In decimal odds, the gambler works out how much they will get from a 5.00 bet where they have staked £10 by multiplying their stake by the number so 10 x 5.00 which gives them £50, £40 profit plus their stake. The outcome is the same as the fractional example above but just expressed in a different way.

There is another type of odds known as American odds. Again, these are just expressed in a different way but essentially mean the same thing. They are also known as Moneyline odds and are expressed in either a positive number or a negative number by assuming a $100 stake.

So if something is 4/1 it would be expressed in American odds as +400 and if something had odds of 1/4 it would be expressed as -400. If something is even odds or 1/1 then it can be displayed as +100 or -100 though not all bookmakers show the plus sign.

All these different expression don’t mean you will win more money, they are just different ways of showing the same thing and are all based on probability. If you are a serious gambler then knowing how all these odds relate to implied probability is pretty important as it will allow you to decipher which bookmakers are offering the best value and can help you to win in better value markets.

How to convert betting odds

Working out how to convert all these different expressions of odds from one to another can be a daunting prospect. Anyone who sat through any algebra as a kid scratching their head will know what we are talking about but fear not, help is at hand.

We have a simple method of converting one to another and will hopefully explain it in clear terms below:

Converting fractional odds to decimal odds

So this is probably the most likely sets of odds you will deal with therefore starting here seems appropriate. Let’s look at how to convert betting odds from fractional to decimal.

It is actually far simpler than you might think. The formula is thus:

To convert fractional odds to decimal, divide the first figure by the second figure add 1.00 (so 6/4 = 6 ÷ 4 = 1.5, then add 1.00 = 2.5).

Here are a few more examples:

13/6 = 13 ÷ 6 = 2.17 + 1.00 = 3.17

24/5 = 24 ÷ 5 = 4.8 + 1.00 = 5.8

1/3 = 1 ÷ 3 = 0.33 + 1.00 = 1.33

Converting decimal odds to fractional odds

You may find that this is the most common change due to the number of sites now preferring to display in decimal even though fractional is still more common especially in the UK.

Below is the formula you will need in order to convert betting odds from decimal to fractional:

To convert decimal odds to fractional, subtract 1.00 and then find the nearest whole integers (so 5.75 – 1.00 becomes 4.75/1, or 19/4).

Here are a few more examples:

(To work out the nearest whole integer for 4.75 put it over 100 so 475/100 then divide this by the lowest common denominator until you get the answer, so in this case five.)

9.00 -1.00 = 8.00/1 = 8/1

4.25 – 1.00 = 3.25/1 = 13/4

1.25 – 1.00 = 0.25/1 = 1/4

How to convert American odds to decimal odds

This will be required less often but the easiest way to convert American or Moneywise odds is to make them decimal odds and then convert them to fractional from there.

Below is the formula you will need to convert betting odds rom American odds to decimal odds:

To convert American odds to decimal, if the American odds are positive, divide by 100 and add 1. If they are negative, divide 100 by the American amount (without the minus sign) and add 1 (so if you have +400 then you would divide by 100 to get 4 then add one to get 5.00). Here are a few more examples:

+650 ÷ 100 = 6.5 + 1 = 7.50

+125 ÷ 100 = 1.25 + 1 = 2.25

-500 (so this is an example of negative American odds) 100 ÷ 500 = 0.2 + 1 = 1.20

Hopefully, these examples are fairly easy to understand and will help you convert odds into whichever format you are happy with.

How to convert betting odds to implied probability

Implied probability is essentially how likely, as a percentage, something is to happen. This will help you understand which markets offer the best value and will aid in making better decision when placing a bet.

To convert the different odds to implied probability use the following formulas:

Converting decimal odds to implied probability

To convert decimal odds to implied probability use the below formula:

(1/decimal odds) x 100 = implied probability

Here are a couple of examples:

(1 ÷ 3.25) x 100 = 30.77% so the chance of team A winning is 30.7%

(1 ÷ 1.15) x 100 = 86.96% so the chance of team B winning will be 86.9% (in this case, this is likely to be for a huge favourite)

Converting fractional odds to implied probability

To convert fractional odds to implied probability use the below formula:

Denominator/ (denominator + numerator) x 100 = implied probability

So if the odds in this example are 13/4 it would be:

4 ÷ (4 + 13) x 100 = 23.5%

If a favourite has odds of 1/3 then implied probability would be higher. Here is the working:

3 ÷ (3 +1) x 100 = 75%

Converting American odds to implied improbability

Firstly, let’s start with negative American odds. Here is the formula:

Negative American odds / (Negative American odds + 100) x 100 = Implied probability

So for odds of -300 it would be as follows:

300 ÷ (300 + 100) x 100 = 75%

Secondly, we have positive American odds. Here is the formula:

100/ (positive American odds + 100) x 100 = Implied probability

So for odds of +300 we would work it out as follows:

100 ÷ (300 + 100) x 100 = 25%